Laboratory-Grown Diamonds: Updates and Identification | GIA Knowledge Sessions Webinar Series

okay let's go ahead and get started welcome everyone to gie a knowledge sessions these are a series of talks and seminars about gemology that are fueled by our decades of research and you know @gi a we rise every morning and we're so privileged and we're so excited to seek and study and learn from gems and it's our mission to share our discoveries with the world so I'm really excited to kick things off today I'm Kelly Giordano member of the content team here at G IA and I'm joined by dr. Mike breeding GI a senior research scientist and he'll be speaking today about something that has a lot of engine interest in the industry right now and that's laboratory-grown diamonds and identification methods so before we get started there's just a bit of housekeeping everyone attending this is automatically muted if you have a question please submit it using the Q&A box on the side of the screen there will be a Q&A session at the end where Mike will have the opportunity to answer some of your questions and we'll also be sending a recording of the session later to you today that message we'll also have a survey and we'd love to hear your feedback about this session so with that I'm gonna go ahead and pass you over to Mike everyone thank you for tuning in today um it's fun to have the opportunity to share with you some of the knowledge that we have about lab-grown diamonds and hopefully address some of the issues or concerns that you have as you go about your daily work like here we go so as Kelly mentioned I'm gonna talk about laboratory diamonds and I'll touch on some of the identification methods but also one of my goals is just give you information about how they're grown and what they are and I always like to start a presentation off with some nice pictures of faceted diamonds so you have some here down the side there are pretty diamonds what you may not realize is that they're all the operatory grown but they're not all grown exactly the same way now I've shown you what the crystals from which from what they were originally grown will look like and you see the top three are very different from the bottom three because there are two major methods by which diamonds are grown in the laboratory one of them is called high pressure high temperature growth and the other is chemical vapor deposition growth so these top ones are HP HD or high pressure high temperature the bottom ones are CVD or chemical vapor deposition you see the starting crystals look very different that's a product of how they're grown and also has something to do with their identification as well going forward let's start out with a little bit of the basics question is what is diamond well diamonds a very simple mineral it's a mineral made purely of carbon atoms there are a few other little impurities that substitute in but the most part it's simply carbon atoms but not just atoms all thrown together they're arranged in a very particular way on the right here you can see each carbon atom is bonded to four other carbon atoms in a tetrahedral arrangement this arrangement is very important as you'll see on the next slide this occurs naturally of course we all value our mind the diamonds but it can also be grown in a laboratory that's why you're tuning in today is to hear more about that the structure of diamond gives us some very unique properties that also mentioned so diamonds not the only material only mineral even made purely of carbon on the left here you see graphite and we all know graphite from the lead and our pencils and it's a very different material than diamond softer among the softest minerals whereas almonds among the hardest that difference is not in the fact that carbon atoms as both minerals are made up purely of carbon atoms but in the structure the left you see graphite it's made of these sort of hexagonal rings and layers that are loosely bonded to each other whereas diamond has this nice tetrahedral structure and framework it makes it more robust the structure itself gives rise to some really cool properties for diamond first as I mentioned it's the highest hardness it ranks as a 10 on Mohs scale of hardness making of the hardest natural material it has the highest thermal conductivity of any other material it's five times a better conductor than copper has the highest molar density of any terrestrial material it sounds kind of convoluted but what that basically means is the atoms are packed so closely together or so than any other material on earth that you'd have to go to a neutron star to find atoms that are more closely packed together and finally one of the more interesting properties as it has the highest sound propagation velocity meaning that if I could talk to you through a diamond you would hear me 50 times faster than you hear me talking to you through the air it's a pretty cool thing and has some important technological application tuned in last week you heard dr. Smith talk about natural diamonds and he told you that most natural diamonds occurred about 150 to 200 kilometers down in the Earth's surface at the base of these bits of continent called cratons they're brought to the surface quite rapidly and violently by magma kimberlites that they end up at the surface where we ultimately find them how they actually get preserved the more exciting things he talked to you about recent discoveries have shown that it below 600 kilometers in the Earth's mantle a lot of the very large type 2 that we really truly rise in value in the industry they seem to occur much deeper in the earth he talked about all that what I'm going to talk to you about is what goes on in these little buildings up here on the Earth's surface that's where diamonds are grown in laboratories so before we start there are some terms that you've probably heard and I'd want to just give a little bit of clarification to them first natural in the context of our discussions natural diamonds are diamonds that grew in the earth and were mined and I'm talking about post growth treatments or anything like that but simply diamonds that originated in the earth these other terms like lab-grown man-made synthetic and even cultured are terms that you hear a lot in the industry and they're referring to all are referring to lab-grown diamonds things like lab-grown man-made in synthetic terms that are acceptable to use to refer to lab-grown diamonds something like cultured on the other hand is a bit misleading and the FTC really strongly discourages its use amongst diamonds but finally don't confuse all of those terms with simulant everything else listed up here is a diamond it has carbon atoms arranged in a tetrahedral structure but a simulant is not diamond even though it sounds something like synthetic it is not in any way the same simulant is a another material that is made to resemble the appearance of diamond used as a substitute now that we've gotten that out of the way in the last few years the lab-grown diamond industry has sort of cranked up and technological advances they've really made them more prominent people are really wondering what that means for the diamond industry what are these headlines we we kind of threw in here for fun and we finally say I do to live grown diamonds will lab-grown diamonds st. save or sink the diamond industry is that rock for real what is a diamond as this perhaps the new diamond Dage so there's a lot of concern a lot of emphasis a lot of curiosity in the world about lab-grown dog as I mentioned in the opening slide lab-grown and natural diamonds are made of the exact same structure the diamond is a diamond whether it's grown in the earth or it's brought in a laboratory and it has the same chemical and physical property but in the jewelry industry we have a need to understand the difference and be able to identify and separate lab-grown diamonds from natural ones there are two growth techniques that are used for lab-grown diamonds the high-pressure high-temperature H PhD technique which tries to simulate conditions on the earth with high pressures and high temperatures in the chemical vapor deposition which we draw here is sort of a fancy looking little microwave because it uses certain types of microwaves to grow diamond in ways that you wouldn't necessarily expect I'm going to be able to grow diamonds have been grown in a laboratory since the mid 1900s so it's not a new thing but only in the last several years have they become prominent industry if you're they call those one sorry to geek out a little with a lot of science but this is important for understanding what we're talking about this diagram on the left is a PT diagram meaning pressure is plotted on the vertical axis going upward and temperature on horizontal axis increasing to the right the areas that are white is where diamond is stable meaning if you have carbon you will crystallize diamond and in the red is where graphite is State all these other little fields that are shaded show you where diamond grows in reality this gray oval is where most natural diamond grows at about five to six Giga Pascal's or GPA and the more thousand degrees C this catalytic HP HT synthesis region this is where high pressure high temperature diamonds are grown in the in the current industry in this area down here in the graphite stability field the metastable CVD diamond is where CVD diamond tends to be grown and you're asking yourself well that's not even in the diamond field and we'll talk about that when we get the CVD diamonds right now I'm gonna start by talking about HP HT growth which is this sort of teal colored field on the right you see a couple of diagrams of crystals it's important to understand that different growth regimes have different crystal shapes natural diamonds tend to grow as octahedra with eight different growth directions whereas HP HT lab-grown diamonds tend to grow as cube octahedron meaning they have a mixture of these a growth directions from the octahedron from similar to natural but also the six directions of cubic growth and for giving you 14 directions for this different shape as a big impact on how we look to identify them so HP HD grown diamonds are grown under very high pressure here you see some anvils six different animals pressing on the sides of the cube and then a high pressure cell in the middle this is where the diamond grows and then I'll show you in a subsequent slide what this little cell looks like but on the right this is a factory it grows HP HT I've grown down and each and one of these green metal devices is one of these presses this factory has just full of them it kind of gives you an idea of this scale of how many diamonds are being grown and how many presses are being employed in the industry when I talk about high pressure what does that mean so by the six of GPA which is about where natural diamonds grow as well as about where HP HT diamonds are grown is roughly the equivalent of about 80 elephants all standing on your big toe on a pinpoint and so it seems silly but that's a lot of pressure and it's a lot of pressure because it's simulating nearly 200 kilometres deep in the earth this high-pressure cell that's in the center of these presses these large animals are pressing anything is the most important part the growing HP HD diamond it consists of a carbon source which is this black area is usually on powdered graphite very pure powdered graphite a middle section which is a metal solvent catalyst it's usually made of iron nickel cobalt and this really facilitates the growth and then at the bottom is a seed crystal and this is a very important part of lab-grown diamond growth is that in order to grow single crystal diamond you need to start with single crystal diamond you need a piece of diamond at the bottom in order to tell the newly growing down exactly what structured of growing but to mimic that tetrahedral we bonded bourbon construction this entire thing is under very high temperatures of 13 to 1600 C as well as very high pressures as I mentioned 5 to 6 GPA what makes this whole process work though is the temperature at the top is hotter than the temperature at the bottom just by a few tens of degrees but what that does is it introduces a temperature gradient whereby the carbon atoms when they're heated they dissolve into the metal catalyst and much like somebody who lives in a hot climate who wants to move to a cold climate they migrate through this solvent catalysts down and then they encounter the seed crystal at the bottom they say ok I see more carbon atoms just like me and they're bonded in a tetrahedral arrangement I'm gonna bond that way - and they slowly migrate down and a diamond crystal grows up from the seat but this gradient in temperature is critical for getting the carbon atoms to migrate down this whole process can take from days to weeks depending on how big of a diamond you want to grow here are some examples of some big lab-grown HP HD diamonds on the left is a four carat vivid orange yellow diamond middle is a fancy deep blue 10 carat faceted stone on the right is a 10 carat olace stone of VES clarity range six seven eight years ago we would have told you that if you see a diamond that's over a couple karats faceted there's no danger it can be a lab grown because they just can't grow them that big I think this shows that in the last several years technology has improved to the point that any sized diamond as a potential the be live grow done you sort of interestingly as well um this diagram which increases from 2000 year 2007 to 2016 on the horizontal axis it's showing the percentage of different colored hph tea I've grown diamonds notice it early on and this is the case since they've been introduced orange and yellow colors dominated but technological advancements have allowed growers to remove nitrogen impurities and nitrogen is very common in the atmosphere so it's very easily incorporated they've been able to remove that nitrogen which causes the yellow and orange color to the point that now there's many more colorless HP HD diamonds that are being produced and today that is probably the most common thing that's being grown by this method not only that technologies that proved to the point that it used to be that they can only grow a single grown diamond in each one of those presses that I showed you now they can grow many all at the same time each of these stones is multiple carats in size they're all grown in the same breasts at the same time over the same time period this is an important advancement it allows a lot more diamond to be grown a couple of years ago we were shown this crystal from a company called new diamond technology in Russia it's my knowledge it's still the largest one that we have seen it's a hundred and three and a half carats it's not a lot to look at and it is yelling long and you but this is where the advancement and growth has come by this method this was grown in two weeks in late 2018 but it's a hundred and three carats which is just absolutely amazing I wouldn't be surprised if the same crystal can be grown larger today and even closer to being colors I wanted to give you a perspective on mold largest that we've seen I'll trust that with what's really if concerned in the diamond industry right now and that is very very small lab-grown diamond by the HP HD technique you see a bunch here on the lower left each one of these little crystals is I've the six point sometimes even less due to three points in size individual HP HT I've grown crystals they're actually grown in these green presses that I showed you the video of earlier and they can grow ends of thousands of carats of these things each month it's pretty amazing most of this growth goes on in China and but it is done in other parts of the world as well each of those little crystals looks like this it starts out with a an industrial quality seed which is even smaller just the scale bar this is about half of a millimeter on that they grow a single colorless H PhD MLA sized diamond on the right you see the faceted versions of these they cut off the C crystal and facet the stone this pile of faceted Mele range anywhere from half a point up to two points in general and that's widely available from China and other parts of the world and it aroused a lot of concern in the industry for Mele mixing between natural and lab-grown I'll make a comment that's light or two about that later on in the talk how do you identify h PhD lab burn diamonds well large or small the best method is if you have inclusions much like natural diamonds will incorporate minerals that they grow around then likewise a lab-grown diamond will incorporate the material in which it's growing I told you these grow in that molten metallic flux made of iron nickel cobalt and you see the inclusions that get trapped and hph tigran diamonds are these metallic very dark looking inclusions they're usually a lobby irregular or rod shaped but they're all metallic and reflective and they look very different than natural inclusion if you see these you can be fairly certain that you have an HP HT grown here's another slide just very just another slide for contrast on the right you see some natural diamond inclusions garnets olivines I know Pyrrhic seen some sulfides on the left you see these metallic flux inclusions and HP HD lab-grown diamonds they don't really look anything alike the only one that has some relative comparison would be the sulfide mineral dr. Smith talked about last week a little bit and some of these deep to a diamonds in the earth but these inclusions tend to expand and cause fractures that graph'it eyes in are filled with dark material and natural diamonds and they tend not to do that in life ground often so even if you see a metallic looking inclusion it's almost always going to have one of these dark halo fractures around it if it's an unnatural not all diamonds have inclusions in them we know that both natural and labrum we need more than just that and this comes back to the morphology remember I showed you the octahedron and the cuboctahedron well here are some natural diamonds that most of which grow either as octahedra like this one over time in the earth they partially dissolved called resorption and they become dodecahedra or more rounded shapes but they're all some variation excluding some of these very deep type two diamonds which are often very irregular like the one in the upper right but well you do know this is none of the natural diamonds have this nice consistent cube octahedral shape that you see from the stones on the left all of which are high pressure high temperature grown I've grown diamonds you have flat cube faces angular octahedral faces mix together in all of well you're probably not gonna be fortunate enough to see too many lab-grown crystals the stones are usually already faceted so what does this help us tells us that the external shape of the crystal is reflected in the internal growth of the crystal and so on the left here you have a cube octahedral schematic if we slice it vertically we can see that from the seed crystal we have cube faces growing up octahedral faces growing at an angle and faces in between you have these mixture of different growth sectors or 3-dimensional regions that have a common crystallographic plane well if you imagine that we we facet this stone so say we cut the table along this line called B to B prime we've got a flat surface here it's cross-cutting these different growth sectors if we go over here and we look at the cross-section on the far right we have a cube sector in the middle making a square shape we have the large octahedral sectors beside it and the ones in between these 101 labelled sectors the square in the middle and the arms coming off the intermediate sectors form a Ross shape and this is very distinctive in diamond and it's important because different impurities like nitrogen and boron are taken up differently in each different growth sector so you get a pattern and when you look at the fluorescence these images are deep UV fluorescence meaning very high-energy ultraviolet light not the kind that you hand shine with a handheld lamp mind you but more something like a diamond view instrument they give you a very nice detail you can see on the right square cube sectors large octahedral sectors and the ones in between Flores very differently creating a square or a cross shape in all of these images this is pretty much diagnostic of HP HD lab grown diamonds and it's very important not only that the color of the growth sectors tells you something you see sort of green or bluish green fluorescence then you know that you're probably dealing with a lab grown diamond and if you turn the UV source off and the Diamonds still glowing fill emitting light phosphorescence another very very strong sign you're dealing with it NH PhD electron diamond very very very very few natural diamonds have these properties there's some examples um these are some colorless H PhD lab room diamonds I hopefully you can see the pattern that less fluorescent Square and arms in each one if you can't there they're drawn in for you the cube and the octahedral grow sectors to make a cuboctahedron birth form and then the strong phosphorescence seen in the lower left hand corner all these are good indicators that you're dealing with a lab grown dime so how does that compare to natural diamonds well here's some examples of the stoppers some more of those H PhD lab grown stones most natural diamonds that show good patterns show squares and this is what you get when you cross cut an octahedron remember an octahedron has eight sides and it's cross-section is a square as they grow larger and larger you get squares inside of squares inside of square sort of square tree rings so reflecting natural growth zones rather than these cube and octahedral mixtures they're very distinctly different in this deep UV fluorescence well not everyone has access to a deep UV device we understand that and there's some cool things that you can actually do with just a handheld UV lamp like the one in the upper right here that does long wave UV and shortwave UV excitation what we've discovered over the years of looking is that the vast majority over the last decade 98% of the colorless HP HT lab room diamonds that we've seen do not full arrest - long wave UV but most of them do fluoresce the shortwave UV that means that if you see a shortwave UV reaction that's stronger than a long wave UV reaction you're probably dealing with a lab-grown diamond fortunately this is gonna hold true for all types of lab-grown diamonds and it is the exact opposite of natural diamond natural diamond tends to fluoresce if it flores's at all if Larissa's to long-wave UV and very little too shortly the takeaway point here is if the shortwave UV reaction is stronger than long way you should be very worried that you might have a lab grown done but we mentioned phosphorescence as well and it shows up the shortwave component of these handheld lamps if you put the shortwave UV light on your diamond and you turn it off in the diamond still glows its phosphorescent this is a very good sign there you're dealing with a lab-grown dye this reaction is called by trace amounts of boron impurities in the diamond that are incorporated during growth in laboratory only a very tiny less than a percent of natural diamonds will have these types of features and when they do they're not as intense as they are and I've burned on you so you're very unlikely you'd ever see that in the natural another trick you can use with a microscope is something called cross polarized filters it's investigating a property called birefringence or the amount of strain in the diamond if you take two polarizing filters similar to what you get in polarizing sunglasses and if you hold them on top of each other and you rotate one of them at some point looking through them it becomes a black because no lights allowed to pass those polarisers have different orientations and when you perfectly cross those orientations light cannot come straight through so diamond is an isotropic mineral this means that effectively that if you shine light through it in different directions the light passes through at the same speed in all those directions if you put an absolutely perfect your diamond underneath in between to cross polarizing plates you won't see any pattern it'll be dark as you look through but natural diamonds because they reside deep in the earth they're under lots of pressure and temperature they get strained meaning their atoms or twisted and moved a little bit they're not perfectly isotropic anymore there was a result when you put a natural diamond between cross polarizing light some of the light gets bent a little bit and it's able to pass through the upper polarizer so you get patterns like those seen on the left two images usually either linear or Criss crossing with different colors ranging from gray or blue to pink or yellow and on how much the diamond has been strained the nice thing is HP HT lab-grown diamonds do not experience any vestrum and so when you put them under cross polar you see no pattern like the samples on the right here there's a very distinct difference between the two this lack of strain pattern is a strong indicator of grown HP HD diamonds now I'm gonna talk about CV DS in a bit and unfortunately this doesn't apply because the CVD growth process will produce patterns similar to natural but if you see no strain pattern then you can be fairly sure you're dealing with a lab grown each PhD chrome dime all right speaking of CVD let's let's go into CVD a little bit now so the same diagram is here but now we're talking about this field down on the bottom this metastable CVD time and we call it metastable because it's in the graphite field meaning urban should not be able to crystallize in the diamond there but it does much of it and it stays diamond much the same way that the ring on your finger with a diamond in it is a diamond and it's not graphite even though we're technically in the graphite stability field at the Earth's surface so the trick with this is the same as the ring on your finger if you can make diamond there's not enough energy you break that diamond apart and turn it into graphite so the trick is getting the diamond to grow at all and they do that with a very specialized approach that I'll illustrate in the next coming slide alright so this slide shows you what a CVD reactor it looks like on the left here it will fit on your standard size table it's not a very big device but the control boxes that are required to run this device can take up an entire room sometimes notice there's a little window here inside that window is where you can see the diamond growing there are lots of little substrates or seed crystals of diamond on which the CVD diamond grows above that is a very hot plasma and above that the gases are placed put into the reactor plasma causes the gases the atoms to break apart the molecules to break into atoms and smaller molecules thus we have a gas phase chemical reaction the gases used are methane and hydrogen and I'll explain you on the next slide why methane and hydrogen are important this whole thing is kept under vacuum so no high pressures here no no elephant sitting on your toe now we're actually below atmospheric pressure and we're temperatures of up to about a thousand degrees C same time period depending on how much you want to grow days two weeks how does all this happen and why is this plasma important that we have to go to the next slide here there we go so this video hopefully is showing for you guys this is a these are all atoms the red atoms are carbon atoms the white atoms are hydrogen atoms so I know it seems a bit overwhelming but bear with me of all the red items in the bottom are the diamond seed crystal of diamond what the grow diamond you have to start with Don all the outer surface of the diamond carbon bonds where the carbon doesn't have another carbon to bond to is bonded to hydrogen because there's hydrogen everywhere in the atmosphere appears the plasma the plasma has different white hydrogen atoms floating around it also has different urban-based see here's a ch3 there's sea ages and ch2s all that are broken up from the methane which starts as ch4 but the plasma causes it to split and other molecules so the single hydrogens are cleaners their sweepers they come down and they pluck single hydrogens off the surface you can see them periodically they'll grab a hydrogen and they're happier it with two hydrogens together when they do that they open up a carbon slot and that carbon slot then allows another carbon atom to come down and bond and it bonds in the same tetrahedral structure is the ones underneath it and we slowly grow diamond one atom at a time upwards by doing this we can make diamond to grow in a place the diamond wouldn't necessarily grow and once we create these bonds they don't break apart anymore so we can slowly atom by atom layer by layer Road I'm hopefully that clarifies that part a little bit all right so when you grow a CV ddiamond it's not so pretty when it comes out it looks more like the one on the left here it's the diamond is the brown that in the middle all around the outside is a whole bunch of polycrystalline diamond this polycrystalline diamond is the material that grows off of the seed crystal underneath this is this is the seed crystal itself there's a whole series of steps that have to be done as you deal with CVD diamond first you grow it and you get this then you need to laser cut the substrate or the C crystal off the yellow part is the C the white is the newly grown CVD diamond we cut right through here and we have to get rid of the outside so we actually laser cut a shape depending on what we want to facet in this case if I want to fast around brilliant I cut a cylinder out of the middle and then I can facet my round brilliant from yours all right so if you cut different shapes you cut different shapes out of the middle if you want to rectangular shape you cut a cube you wanted to grow up more than one round diamonds out of the st. piece you might cut a cube and then angle the growth or the cut direction of the dime the takeaway point of this is that unlike H PhD I've burned diamonds where you just get the crystalline facet it you have to do a whole lot more with sieve it either several steps not only that you probably noticed that that diamond was brown and you're like most I've grown diamonds are not brown well it's much easier to grow CVD Diamond Brown and much faster actually and they discovered several years ago that you can take this diamond and you can put it in a device very similar to that which HP HD diamond has grown and treat it in a way that decolorize --is it natural diamond can be decolorized the same way it goes from brown near colorless and you can do this in a matter of minutes so it's much more efficient to grow as brown and HP HT treat new colors in fact over a long period of time over a decade we looked at all the CVD diamonds we had seen and nearly 3/4 of them have been decolorized by this method so it's very very common what this does introduce though are two distinctly different sets of properties for identification when you have the as grown CVD and you have the treated CVD it changes some of the fluorescence and other properties so we have to look at each one of those separately so much like I mentioned with the HP HT diamonds few 7-8 years ago we would have told you if your diamonds bigger than two carats it can't be like grown even more so with CVD because it's a much more difficult growth process but here are some some examples to show that this day and age that doesn't apply at all notice the colors and the clarity is on some of these they're quite spectacular five karats 6 carats the equivalence of colors very slightly included clarity range all the way up to the largest that we know about right now in faceted CVD which is 9 over 9 carats so there's some very large some very nice CVD diamond I wanted to give you a bit of a timeline because I talk about how things change and I thought this was kind of fun going from about 2003 up to about 2008 mm-hmm on the vertical axis is the carat weight but you you can just look at the chart itself the initial diamonds up to about 2008 cvd stones we saw never really got much larger than a carat faceted never brown and somewhere between 2008 2010 they learned how to decolorize then or occasionally grow them coalesced very very slowly but then we noticed that 2013 the size increased the two carrots and then 2015-2016 it really started to take off the technology advanced to the point that we really started to see big stones three carats five carats and then in May of 2018 we got reports of this 9 carat faceted stone it also started seeing treated color CVB's getting very nice and tense pinkish orange colors but not just colors they can also be colored this gives you a bit of a timeframe and how much the technology has really taken off in the last five years pretty remarkable well much like the others in the other lab growing diamonds cv DS also occurs Mele this is just an example from a parcel that was sent into a GI a laboratory for examination 30 carats all consisting of six six point stones of this 546 Mele 542 of them were CV de grown only four were natural and this is highly unusual but it's to show you that cvd Mele is out there the H PhD Mele is far more common but CVD is sometimes cut into melody as well so you can't discount that idea looking at some identification features um we I talked about how important inclusions were to the other types of lab room diamond well in CVD they're not quite as valuable because most CVD these are very high clarity chart on the right shows you that it's a simply percentage of CVD diamonds and you see the vast majority are in the vias BVS range of clarity they go all the way up to internally flawless if they do have inclusions they tend to have these little black wispy none diamond carbon inclusions sort of as you see in the lower left some natural diamonds can have these types of features if you do see these I would say be very wary and actually a few weeks ago in the laboratory I saw a CVD diamond that had something looking very very similar to this and so keep your eye out that's they're not always there so it's not nearly as strong of an identification tool as it is in the HB HD brownstone so we talked about the cube octahedral growth for the HP HT diamonds it's a vertical cube growth for CV DS but has an effect on the growth shape because while most of the growth is going upward at the same time there's a little tiny bit of lateral growth on a microscopic scale what it does is it creates sort of a pseudo mini micro stair-step structure Rises or steps and little intermediate growth sectors which we can refer to as striations because they're so tiny they just look like lines when they incorporate different impurities in the fluorescence what does that mean well let's let's look I apologize I want to talk about growth first it'll be on the next slide the striations it's hard to grow CVD diamond for a very long period of time without something going wrong so initially they would grow as thick as they could and they would develop these striations which it are an angles to the substrate but we didn't get large CVD diamonds because it's very hard to grow thick enough to get a large diamond cut out so what growers started doing is interrupted or layered to growth well they'll grow a little bit they take it out they polish it and they put it back in they grow a little more they polish it then they grow a little more you still get the striations and the layers from the growth but you also get growth interruptions and each time you stop some impurities are taken up in the structure and they fluoresce different let's see what I'm talking about so these are as grown CVD diamonds they fluoresce either orange or red typically and you see all these little subtle parallel lines some of them look angled but it's mainly due to the faceting the way the faceting is showing here but these repeating lines are striation these are unique features to CVD diamond UV fluorescence here we're looking at again on the right you see the striations are in each layer but you see very distinct layers sort of like a layer cake each one of these growth interruptions is where they started and stopped the growth so that they could grow thicker and thicker and thicker so it kind of gives you an idea that the fluorescence really gives away that these are CVD diamonds you don't see these textures and natural those were as grown these are the ones that were decolorized by treatment and you notice we still get the very nice striations we just get a very different background color here we have different defects or imperfections in the diamond structure that's causing the fluorescence to be a different color but the structure the striations and the growth interruptions are still the same which is pretty fantastic when you're trying to identify these things that they that part at least doesn't change with treatment much like HP HD you can do a little bit with your handheld UV lamp as well even more so than HP HD very few to any basically no CVD diamonds will flow arrest to long-wave UV whereas most natural diamonds do that means that if you see a shortwave reaction stronger than a long way reaction again it's likely lab-grown doesn't tell you CBD versus HP HT but it's a good indicator that you're dealing with a lab grown and I'm assuming that most of you probably don't care whether you're dealing with the CVD or an HP HD just that you're dealing with a lab grown document versus a natural one so note having this difference in reaction is critical with a simple handheld lamp now a starts to get a little tricky with phosphorescence because as grown CVD diamonds don't always phosphorous usually those that have been decolorized which as I told you earlier is nearly three-quarters of the stones we've seen will have a greenish phosphorescence the shortwave UV and so when you see this phosphorescence the shortwave UV then you can really be concerned you might have a lab-grown time all right and then something on advanced instrumentation there's an interesting impurity that goes into CVD lab-grown diamonds and this is the just nitrogen and boron as an impurity but silicon which is very very very rare for natural diamonds but it's fairly common in CVD grown diamonds that's because this little window and the reactor and some other quartz containing components within the reactor get etched to by the very hot plasma and the silicon atoms get brought into the plasma and then they can drop in the vacant spots in the atom in the diamond structure that's growing and be incorporated within the diamond using a very sensitive technique called photo let's we can measure light coming from these silicon atoms as these very distinct sharp peaks at seven thirty six point six and point nine nanometer positions this tells us unequivocally that silicon is present in the diamond lattice and so when you see silicon you assume CVD done that's very very good all right so quickly I want to touch on some developments I know I'm running a little long here I apologize but if you've heard of lightbox lightboxes new line of CVD synthetic diamonds that are being marketed by company called ln6 which is owned by De Beers we I think pretty sure they sell them as blue color so in pink but they're all as grown CVD diamonds and we saw a couple samples when they were launched and they're very nice stones and the near coast range very good cuts and very high clarity's as well like Marc's diamonds have a very distinct logo etched just below the diamond surface you can see pretty distinctly with a microscope but probably the most important factor is that when De Beers entered this industry they really did some interesting things in pricing they priced one carat stones at $800 and that is far below most lab-grown diamonds and particular CVD lab-grown diamonds had been priced previously they were done as a percentage of the natural diamond process so this really sort of shook up the diamond the lab-grown dime dentistry in terms of pricing a bit and has really led to some changes there also when to talk to you about some things we've seen in the laboratory these are not common but they do occur where natural diamond is used as the seat crystal and on it is CVD has grown this instance the billion of this round of brilliant is a natural diamond and the crown is CVD in this case the CVD was grown to add weight and it adds nearly 30% of the weight of this stone in lab-grown diamond these are sort of mixtures or hybrids or whatever you want to call them we don't have a formal term for them but they're mixtures of natural diamond with lab-grown CVD diamond on top you can't do this with HP HD grown diamond as well because the seed is always removed but if you use the natural diamond on which to grow the CVD it's a much more viable thing DP UV fluorescence shows us the blue fluorescence it's typical of natural diamond and then sort of paint that comes from as grown along those same longings um we've seen stones we're extremely thin layers like this 80 micron layer which is about the thickness of a human hair of boron doped see fede was grown on a natural diamond the boron causes blue color in the diamond and it gave this diamond just this tiny little bit on top gave this diamond enough to be called fancy blue by the color grading system it's less than point zero eight millimeters it's absolutely amazing but the deep UV imaging shows us the pavilion the natural part fluoresce is blue and the crown fluoresce is green which is very very different and so it helps us separate it but I just want to make you aware that these sort of hybrid mixed natural and lab-grown diamonds are actually occasionally produced I don't know how prominently we've only seen a handful of them but there certainly are out you I should have mentioned here that um on the lower left you see some arrows this is not really visible in the microscope there is a tiny feature there after you know it's there that you might recognize but I could I saw this done I could not see it most of the gemologist could not see it either without being told that it was there so it's something that you have to be very very aware of if you used a tester on the crown versus on the pavilion of one of these Dunn's you probably get different testing results it's a good thing to keep in mind all right so you may know the diamond pipeline from exploration to mining cutting grading and retail now with lab-grown diamonds being more prominent we've got a parallel structure where we have lab development and factory growth sort of parallel the natural diamond industry but everything gets funneled into the same cutting grading and retail sections and that makes it critically important that the grading of gem labs can't separate them but also more that you are able to screen diamonds as well and why is it important because I talk to you so much about Melly earlier and this is this ring has 70 Melly diamonds in it well one of them that one is lab-grown each PhD lab-grown diamond the rest are natural done very very difficult to know that without having the types of equipment that would allow you to do that maybe the ability to test the individual stones or in the case of deep UV fluorescence over here you can see that the greenish blue fluorescence and the strong phosphorescence give it away but you have to know to do this and you have to have the ability to test and most people don't have BBV available to them as a result there been a lot of diamond screening devices that have entered the market in the last many years these are just a few of those available I just gathered some different snapshots but there's a ton of different ones and they use different technologies and I'm gonna just briefly touch over the last couple of slides on those technologies there are six main technologies that are in play when you look at all of these types of instruments they involve UV transparency or the ability to pass you the light through a stone UV visible absorption which is the same thing just using a spectrometer to measure a spectrum infrared absorption spectroscopy which involves passing infrared light through phosphorescence imaging which is measuring that phosphorescent property by taking images of stones once you turn the UV light off using spectra to measure the decay or how long that phosphorescence takes to go away and then finally looking at fluorescence spectroscopy or collecting spectra from stones while the UV light is on to measure the fluorescence produced by the defects that are present these techniques are incorporated in various different machines but I'm gonna comment just on four of them and talk about some of the advantages in disadvantage because these are the most prominent ones UV transparency is predicated on the amount of nitrogen impurity that's in a diamond so polis lab-grown diamonds are type 2 meaning they have no measurable nitrogen and that's why their colas so UV light should pass through them if the diamond has nitrogen in a natural and it tends to absorb the UV and it does not pass through this is the easiest method to do and it costs the least and it's been around and screening devices there for the longest time infrared absorption spectroscopy collecting an infrared spectrum this is the fundamental way that diamond type like 1 type 2 or nitrogen and boron impurities are measured so obviously if you're trying to separate type 1 and type 2 diamonds this is the fundamental way to go loss for essence imaging is the most common amongst devices because it's the easiest you build unnecessarily easy to do but the easiest to build as a device because you're just taking images and it's very visual people like visual things then finally fluorescence spectroscopy and this is important because you're looking at defects that come from natural features you're not necessarily looking for what is lab-grown about the stone but what makes it natural so each of these has some disadvantages and you should be aware of these I'm not saying ones necessarily better than the other but you should be aware of their limitation UV transparency can miss synthetic diamonds or lab-grown diamonds and it can pass simulants because for when it's assuming that you're using diamond and there's some lab-grown diamonds that will absorb UV light like natural diamonds do it also has a very high false referral rate infrared absorption spectroscopy if you have stones with poor clarity you can't get the light through that's a big problem and the analysis is relatively slow it takes longer to collect a spectrum phosphorescence imaging it's nice it's visual but unfortunately you notice I told you that some of the treated CV DS phosphorous some don't most of the as grown CV DS do not phosphorus very well so if there's no phosphorescence this technique assumes that you're dealing with a natural diamond likewise it assumes that you're putting diamond in so we can pass simulants as well something I didn't talk a lot about that there's also a way to take but have grown diamonds that phosphorus and they were radiation treatment on them and you can actually reduce or eliminate their phosphorescence and if that's employed a technique that's looking for phosphorescence would be fooled and it would allow lab-grown diamonds to pass as natural with fluorescence spectroscopy which is one of the more robust weapons it does have the problem in that it because it's looking for natural features it may not always see those in every natural diamond so it may refer a small percentage of natural diamond so with that being said I'm not gonna comment on the quality of any devices but I wanted to make you aware that there are organizations like the diamond producers Association that have done testing on different screening devices and they make that testing available to you under something called project - sure you go to the diamond producers Association website under project - sure you can download the test results for any device they tested and they did quite a lot here I show you just the results for GI A's ID 100 which separates natural and lab-grown diamonds so if you go down through you get lots of information about the device and I apologize this is a little blurry but this is way below the key Bart's are in the test results the diamond - false positive test rate is how many natural diamonds did the device call a lab grown in our case it was zero in the synthetic and false positive rate how many synthetics did it call natural we tested as a zero which is great and then finally the simulant false positive rate how many stimulants did it called diamond zero so these are the key numbers if you're gonna use the device you want to make sure that it's not gonna call natural i've grown or simulants the wrong thing so i encourage you to go have a look if you're interested in buying a device there's a lot of good data on here and it'll give you some some very good information about each of those different devices so with that I'm gonna stop here and I wanted to let you know also that myself and some of my colleagues have authored some very nice articles with a lot of this information and even more and our journal gems entomology those are available on at the GI a website for free going just download them the two articles that are mainly of interests are about CVD grown diamonds and HP HD grown diamonds 2016-2017 so go have a look if you want more information I think it'd be really useful aside from that hopefully I can I can answer a couple questions here at the end then I hope this has been useful information and and that you've enjoyed thank you so much Mike that was all such fantastic information we do have a few questions from the audience I will mention some people were asking about the GI a ID 100 if you go to store dot G iae tu you'll be able to find more information about the device including the price and so then let's get right into some of the questions about lab-grown diamonds so first on the list what what is the best way or I guess is there even a way to cite ID a lab-grown diamond an ID is dangerous and most any aspect of identification if you mean just just looking at it without any sort of magnification it's not something I would recommend ever Tron I don't think there's a reliable method for that if you have a microscope or even a loop immediately go and look for inclusions those metallic inclusions are very distinctive and they're quite common amongst h ph d-- grown diamonds if you see them great probably lab-grown if you don't see them you can't really assume anything because CVD don't usually have inclusions and natural sometimes do not as well you see natural crystals great it's natural you see metallic flux its h ph d Garn synthetic you don't see anything you got to be really careful great should the seed crystal be natural or could this seed crystal be a synthetic diamond that's a good question um typically the see crystals are art lab-grown diamonds because it's nobody really wants to slice up their natural diamonds into into plates the to grow diamond on it's much more expensive there's another reason that lab-grown diamonds and usually HP HT lab-grown diamonds are used is because if you have imperfections in the diamond structure in the seed crystal those tend to grow into your newly grown lab-grown diamond so you want the purest thing that you can get and as I showed you from the strain the HP HT lab-grown crystals tend to be the best structure the purest structure so they're usually used that being said you can grow diamond on diamond it can be natural it could be lab grown CVD or HP HD synthetic either way so you you just need diamond but it's most commonly and just let everyone know we are just about out of time but I'm if anyone who can stay can stick around we have a few more good questions so we'll uh I just want to let everyone know that we will go a little long we have another question about the seed you said in HT h p HT process that the seed is removed does it get used again yes they have to republish it and clean it up but they try and reuse their seeds from both processes actually because it gets removed from CVD as well and they use lasers to cut them with H PhD this is much easier to get the seed off it's not as here it is uniformly because we're not talking atom by atom layer by layer girl but they reuse in both types of and that it growth okay now as crystal growth is sped up does that increase any impurities or dislocations yes that's why they well H PhD growth occurs at a fairly uniform rate you can't really speed it up you put it in the reactor and it grows over a certain real time the size your crystal is contingent upon how long you let it with CVD the rate is very important it's the slower you go the fewer impurities that are taken up with this atom-by-atom growth there's a lot of opportunity for other things to get stuck in there and so yeah the slower grow the better but it's not cost-effective to grow super slow and they found that if they add a little bit of nitrogen impurity they can grow faster for CVD but that's where that brown color comes from that's they need to decolorize them okay is there any reason why diamonds can't form an octahedron during HP HT and do you think that with advancements in technology that that could actually become a reality the girl excuse me the growth shape has to do with the pressure and temperature conditions as well as the time over which the crystals growing natural diamonds grow over a long period of time at lower lower temperatures and about the same pressure as HP HT grown synthetics but in order to grow effectively they need to increase the temperature in the HP HT growth process so that they can do it in days to weeks and not take a million years and when you do that you end up with a cube of a mixture of Kuban octahedral growth so no it's not of not a viable expectation that that's going to be eliminated okay what defect causes fluorescence and phosphorescence in laboratory grown diamonds and can may fluoresce any color besides bluish yellowish and greenish yeah keep in mind that a lot of the images I showed you were deep UV images fluorescence is something that I've studied a lot and it you have to be careful because the excitation wavelength that you use the energy of the UV light will affect the color of the fluorescence that you see so the greenish bluish is what we typically see under deep UV very common it's caused by boron that's incorporated in the H PhD grown diamonds and the the defect is a boron related defect that causes both that color and the phosphorescence there are plenty of defects that cause different colors of fluorescence the reason you see the change from the sort of pinkish or reddish fluorescence in the as grown CV DS that defect is called a nitrogen vacancy Center that creates the red fluorescence as you decolorize that diamond by treating it you change that nitrogen vacancy defect into a defect that consists of two nitrogen's and a vacancy that defect fluorescence green which is why you see the change the blue green and that that instance so each case is a little bit different there are all caused by different defects but it's very quantifiable unfortunately that's another hour to two hour long like I'll do it so that's great well we'll add that to the list for future knowledge sessions okay so I think you know we're about five minutes over so I think this is probably a good time to end it I know they're there a bunch of other questions that we didn't get to so if you wanted to reach out to us and ask any more questions feel feel free to connect with Dia on any of our social media or go ahead and go to gi8 edu and go to contact us and let us know if you had any other questions we'll also be sending an email to everyone that registered with a link to this presentation in full and we'll also include a survey there so again we'd love to get your feedback so thank you so much dr. breeding this is like you know such a great session with so much information so thanks for everyone for attending and don't forget to tune in next week where we'll be joined by Aaron Paul key to talk about gi's field demolish and colored stone origin determination thanks everyone bye everyone

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Length: 63min 52sec (3832 seconds)

Published: Fri Apr 17 2020