Risk vs. Reward: Cutting a 161 ct Rough Coober Pedy Opal Gemstone

while back I received an email from an opal miner at Cooper PD asking me if I wanted to buy this 160 karat chunk of rough opal his beautiful colors every color red green blue yellow he rubbed the top of it off and you could see the color from the top despite the poach around the edges and that there was a thick layer of pots on the back so I've got a 160 carat opal but how much of it is really usable opal is the question that's the risk or reward the side this side is a disaster mostly Potch some holes in it kind of kind of a bad thing this is this side looks like a minefield with sand and pits and discoloration and almost no colorful opal so should I buy it or not it would it be worth it well on the basis of the extreme beauty of this side and this extended into the stone I decided that I would buy it here's a specimen the edges are dark this is a side that would look so good in the photographs he he embellished it a little bit with Photoshop I suppose but it's pretty much true you can see that central areas and a lot of blue at the edges there is sand and these darker areas that are peculiar to me the back side there is terrible and here I've started to smooth it and it's smooth but it's showing me the same thing I saw one before i smoothed it that is there's a lot of pot there are a lot of defects cracks holes I worked the top down and remove the sand from the top and a little bit of red is showing through at the edge in that darker area so I need to grind down a little bit further and remove this here I've gone down a little further and the sand is less and the sides look about well pretty much as before I have not worked on them I will do that here starting to put a little bit of a curvature on the surface and you can see the outer part is a little bit darker than the part on the right that is light this is the front of the stone the back of the stone has a lot of pot and that central area of color I've marked it here to cut it in half but I didn't cut it at that time here it is pretty much finished for the moment beautiful color appears to be in the center so if I need to get to that the really nice material I have to actually cut this in half this is the front it's wet it looks dark here it is dry and it's lighter so there's a nice large area on the front to make a beautiful opal that's a lighter color and on the back we can see that there's an area that's good but most of it is Podge so the front has light opal in the center but at the periphery it's dark and I suspected that in the middle we might get the same thing I marked this area as an area that might make a nice cabochon so I finally marked it for cutting in half the technique that I'm using here is different from the technique that I used in a previous video this is what I call the rolling technique you draw a line around the edge and you follow it and you keep going until you get all the way through the other method that I use is what I call the push through method you draw a line all the way around you put the line on the saw blade and just push and if it goes all the way through and stays on the line it's great you get a nice smooth cut but if it doesn't you end up with one that's too thin one that's too thick lots of problems so this worked out pretty well I successfully cut it in half and on the inside is some of the best-looking dark base or darker base opal that I've ever seen lots of reds you can see those scars from the rotating method as the backside which is smaller than the front but both are usable and we just have to take it as we see it this is the back it was weighed about 10 carats at this point and has those marks on it this is the front and I want to make a cabochon but I'm gonna have to get rid of those scratch marks and that will take some work I used a template to mark an oval area for the cabochon and put areas that I thought I'd saw it 3 saw marks but as it turns out I only needed two cuts and I got around in the area so this is the front it's lighter opal and on the back is darker opal and I decided to make a two-sided stone not knowing which one would come out best so I rounded these edges off smoothed it domed it domed both sides and this is a finished product I'm sorry I don't have the footage of my cutting mat but this is just before our policy nice light side and the back is a darker but beautiful opal and here is the the front side on the top stick right after I polished it it's a really attractive stone here it is in different light you can see it's really very very nice down I was sent this pendant this is changing the subject but the person won't have wanted me to change the opal to something better so I used the back part that the small half of the specimen I said this would make a great replacement stone but I have to cut it down shape it and then I have to put the dome on the flat side here the flat side with all the scratches from my rotating technique of cutting it in half but the the I was shaping it here but the ultimate thing is - this is sorry this is a little too fast I'm not nervous but I'm just shaping it a little there's nothing significant going on here please avert your eyes is this is a side I want to use and once again this chattery fast motion of me smoothing it and just getting it to about the right size it's at about the right size where I can size it for the stone that I'm replacing I don't really need this whole thing so I marked an area and cut it with a trim saw and the top part the large part I'm going to use for the to replace the opal in this setting and I think it'll make a nice replacement when you're making an opal pendant you have to orient the stone so that the color faces forward and that is about the way it ought to be so I'm make the oval in with that orientation I'm smoothing the edges around I'm approximately the right shape but in size but we need to put a dome on this back it's flat the edges are thick so the first thing to do realizing that the center part of the stone is going to be the surface it's going to be the dome I have to go and and lower the edges make the edges thinner and leave that the center part untouched for the moment grinding the edge down trying to get it down so that we can put a dome on in the center where it should be and here we can see that it's not quite dome shaped I've got a dome on it but it's a little bit of a problem here it is dry and it looks good looks dome shaped and wetting it simulates a polish so it looks really good but this one little area that right there it's a scratch so I eventually worked on it smoothed it out polished it set it in the opal set it in the pendant and I think it's pretty pretty successful so here are the two stones this is the backside of the big stone that's the front side of the big stone and here it is the back side and we've got a total of about 26 carats here and along with about 13 other carats in scrap and I think I did well overall

Channel: Pulitzer Opal

Views: 694,885

Rating: 4.7510371 out of 5

Keywords: drp, drpopal, rough opal, rough, beautiful, Australian, Coober Pedy, Lightning Ridge, black, black opal, cutting, flashy, mining, polishing, risk, reward, risk reward

Id: UmrhKo8p5tE

Length: 10min 54sec (654 seconds)

Published: Wed Dec 27 2017

Reddit Comments

[u/CrotasMinion]

Wow. That was amazingly interesting. I wonder what he paid for the initial stone and what his return could be based on the two main stones he created plus the 13.6 k in scraps.