Hi, I'm Steve Moriarty from Moriarty's Gem Art. We're a jeweler on the square in Crown Point, and we're also available online at and


Today, what we're gonna talk about is this beast. This I've been putting off cutting for about six months now. It's time to get to it. The reasons that have held me back on this is because of the difficulties of the inclusions that are in it to deal with and also a little bit of fear, because I've seen a piece like this before. Actually, it fractured on me while I was cutting, and it was gonna cut a 100-carat stone. This one will probably cut a 30, and a second stone on this side, that's probably gonna be somewhere around 10 carat.


So, over the next week or so, we're gonna run through the process of cutting this and show you cutters the difficulties that I have to deal with. Hopefully, we'll end up with a couple of beautiful stones when we're done.


This is a natural color tanzanite. This is how it was mined. It has very pure colors, no green to it, not an extremely dark color, but really a nice crystal. I'm gonna show you what the dichroic colors or trichroic colors in the natural tanzanite look like. Let me see if I can get this right. How does that look? So, this should be the purple and yellow, that may be the blue and yellow, and this direction is maybe the blue and the purple. I can't see it, so I'm just doing it from memory.


The yellow color that you see in there ... What's gonna happen is, once I've cut this stone and get all the inclusions out, because inclusions tend to break once you start heating these ... because we're gonna heat this to a 1,000 degrees ... That yellow is gonna disappear and just leave the blue and purple, and that's what we expect from tanzanite. That yellow is kind of making this look like diesel. They call this diesel. It's kind of a brownish, reddish color. Once it's heated, that's gonna disappear, and we should have a couple of beautiful tanzanites.


All right. This is our crystal ... very, very clear crystal side. Don't really have to use immersion fluids. If I had an issue that the surface was rough and I couldn't see into it easily ... You can use wintergreen oil. This is available online. It's just pure wintergreen oil. That's got a refractive index of maybe 1.52. On most gems it's very helpful. You can either just wipe it on the surface, or you can immerse it and look into the gem. You can use the lighter, you can use your flashlight. Now, I have looked at this in the scope and used the visor, and I've tried to plot out a map, showing where all my inclusions are, so I can try and figure out what to cut from this. We've got issues of the way this crystal is shaped on the back. The angle that it's at, we have to consider.


Let's take a look at the map I've made of this stone. I've plotted out all the inclusions and the different sizes. First of all, there's lot of inclusions up here at the top, so I've exed them out. That's unusable material. I'll show you that. Those inclusions are up in here. They're in both tips of both these crystals, so we're just gonna cut that away. The next inclusion that's a problem runs right across here. It's 5.5 millimeters from the edge, and I've got about 20 millimeters height. We've got about 30 millimeters across this way. So, my usable depth on this is 12 millimeters. The actual depth at this point is 14.7 millimeters.


Let me show you that. This is the inclusion that I've got to deal with. I've estimated its depth ... These often run deeper than you expect. You assume, if you think it's two millimeters, it's two and a half, three millimeters. You'll find that, through all you're cutting, everything is deeper than what you think. But I've tried to estimate it well. The other issue ... Because it's a twin crystal, there's usually a plane that runs through here, and in some pieces you can see absolutely that there's a visual plane. In this piece you can't see it, but I'm gonna assume it is, and that we're not gonna cut across that plane. I'll show you that in another picture.


This Is between the two crystals. You can see this plane that runs here. I'm not sure ... I think this is the plane we're gonna deal with, and we're gonna saw it right across that, right through here. We're gonna cut a stone here and then cut a stone here. So, this is the plane we're gonna saw through next. This is the inclusion I have to deal with. I have determined that this inclusion side is gonna be my pavilion. I look at this point being where the culet will be. I do some kind of brilliant cut. The cut is naturally gonna go above this inclusion if I predicted the depth correctly.


Now we're gonna saw the crystal across that line that separates the twin crystals, and then we'll determine what we're gonna get from it. So, I've cut this little point here, that's kind of in the way of getting a straight cut down the crystal. So, I've got to try and cut into that slightly, make room that I can line the saw up. Okay, hit it. All right, I got rid of that little crystal tip. Now I should be able to hit this line again. You can maybe see the line I'm gonna cut down.


So, as I was cutting, it split right along that line. There was a weak point there, but it split perfectly for me. I didn't even have to saw it all. That means that during cutting it probably would have split there, if I tried to cut it across that crystal. You can see. I cut maybe a third of the way down, and then it just split along that line. It's exactly the line that showed, that came out the bottom of this stone. There is another line over here, so I hope it's not an issue with that, but we'll find out when we start cutting this bigger piece.


So, we've got our two pieces now. We'll dop them up, and I'll cut away the bad parts of it, see what I've got left and determine just what cut I'm gonna do with these two. Before I dop this up, I'm gonna take out the problems that are in the tip and work on the shape a little bit. It just makes it easier to figure out what the center of the stone is when you're dopping. This lap, I believe is probably about a 400. I'm not using very coarse right now. I'm just going across the dop to try and more evenly ... across the lap to more evenly use the diamond that's in it. That's got most everything out of this crystal. Now I'll more easily find the center when I'm doping it. Then the same with this one. The inclusions go a little further in this piece.


All right. Here is our finished preforms. They're both looking kind of square cushiony to me. This started out as a 112 carat, currently we're about 101 carats. This is a 66-carat piece. Now, this piece measures 18 by 18 by 14. If you want to figure out the percentage depth, that is you take the depth and divide it by the width. That gives us 77% on this stone. 77% is a deep enough material that you can cut it properly. The other piece ... This weighs 35 carat, measures 15 by 15 by 11. If we divide 11 by 15, we get 73%. This can be somewhere between 73% and 80% depth. So, like I say, it's looking like some kind of cushion. I do have this issue here that I'm gonna have to match all the way around it, but looking at this, I'm estimating maybe 40% out of these piece, rough ... possibly 45%, but probably 40%. So, we're gonna get somewhere between 12 and 15 carat out of this piece and maybe 25 to 30 carat of out this piece.


Next, we're gonna dop this up and get ready for cutting. I'm gonna first dop this larger piece of tanzanite, the 66-carat piece. I want to cut the pavilion first, so I'm gonna dop the opposite side of the side with the big crack in it. First of all, I use some dental wax, that's available from any drug store, nice and sticky ... and will form to the stone and hold it in place, once you get it centered the way you want it. I'm using a dop that's about the size of the stone I have to use as a centering device. Make sure there's no flats on it, because often we'll be cutting, and we'll cut into the dop. So, pick one that's nice and round. It's a very helpful device in centering your stone.


Now I think that I have it centered, just press it into the wax. I'm gonna find the right dop that's appropriate in size, to glue the stone up. Then, I'm also gonna follow through and check my measurement with a millimeter gauge, just to make sure I'm accurate.


I'm ready to mix some glue and dop this up. It's often best if you dop under the dop, but it's also harder to get off. My greatest fear is that this piece of material's like one that broke on me when I was trying to heat this dop loose. I started just putting glue around the edge, and then I can peel it off and easily remove it. That's what I'm gonna do with this stone, just because this stone reminds me so much of that one that blew up on me ... that I'm gonna try and not put too much heat to this, even though I have to heat it to a 1,000 degrees later. I'm gonna just dop around the edge. Like I say, in most stones, if they will take the heat, and you know that they're not really heat-sensitive, you should dop beneath the dop. It will hold better, you won't have the problem of falling off.


But this time, I'm just gonna put it around the edge. Now, I've previously cleaned the stone and the dop with alcohol and made sure all the epoxy was off it. So, we're just gonna mix equal parts of this epoxy. It's a big stone, so we need to have plenty of glue. Okay, that should be good. What I'm gonna do is put the glue up further on the dop and let it just drip down onto it. Then it won't get under the stone. Like I say, the risk of this is that it breaks free, because you don't have that extra support between the dop directly and the stone, but I'll be able to just pick this off and have less risk of causing damage from heating up the dop too much and actually causing problem with the stone. Like I say, it seldom happens, but it happened on a tanzanite just like this.


Just manipulate it, so you don't get the glue over the edge of the stone. I don't want to be cutting in the glue, it's tough on the lap, and it takes a long time to cut through glue. This will need to set, ideally, over night, but at least three or four hours before we go cutting.


So, it's been about seven hours, and we should be good and hard. Hopefully, it will stay on the dap for me. Let's take it out of the transfer block. Making sure everything's good and tight, visually square it up ... Now, I'm gonna try and get it square. If you look at it closely, you can see that pretty big corner here that I have to deal with. So, one way or another, it's gonna have to be matched up on all four sides. First, I'm gonna cut it 90 degrees and get the four-side square. I'm cutting with a lap that's about a 400 grit. I'm just gonna check and see how square I am. It's pretty well centered. I got the dop and center of the piece pretty well.


So, now we're fairly well squared up. I still have this issue, the girdle is not all the way over here, but we're not gonna cut a square. We're cutting a cushion shape, so there'll be some angles that will take this material and get me an even girdle all the way around, hopefully.


I've run into a bit of an issue here. On this corner here, you can see where that line is ... It appears to run a little deeper than I expected. What I'm gonna do first is ... Seeing as I know I'm gonna have to get rid of this amount of material, at least on this side, I can cut that, and I know I'm not gonna be losing anything. I'm gonna cut there and see what's left of that inclusion when I'm done. It is possible I may have to change the cut style I'm doing. I can see it can be a shield if this is a problem that runs too deep. So, I'm gonna cut a little bit on this facet that has got me out of square a little bit, but I'm gonna cut the matching facet to the other side and see what that inclusion looks like.


This is the part of the stone that's like a facet on the girdle that's got me out of square. That is material I had to deal with, but I can cut on this side and take the equivalent amount of material and see what's left of that inclusion before I proceed. [inaudible 00:22:52]. It does go a little deeper than I thought. I'm not sure if it's above my girdle, but I may miss it. It looks like it could be a problem, so I'm gonna try and analyze this a little more, and I'll get back with you with what I decide to do.


So, this is something that something happens, inclusion that you know are there, but you don't know exactly how deep they run. Looking at this, it runs deeper than I thought, so making this a square cushion is probably not gonna be possible. What I'm gonna do ... I'm gonna cut a little more through this inclusion, try and get most of it out, and then, because I won't be square on the dop now, I'm gonna have to remove this stone and re-dop it to the center. So, it's gonna create a few more problems, because that inclusion I'm trying to miss that's up here is gonna get closer to the culet to the center. It's gonna create a little more problem. This is why I put this stone off for so long, because I knew it was gonna be trouble, but I think we'll get through it. It's just gonna create a little more work.


So, I continue to run into issues with this stone. I've gotten most of the one problem inclusion, and I'm now down to 56 carats. You know, this is where this wintergreen oil comes in handy, because this roughened surface from the cutting lap ... Now when we put the oil on it, you can easily see into the stone through that rough surface. The problem I was cutting out is right here, but ... Can you see it? But if we look further, there's a plane that runs across this direction. I'm not gonna be able to get that completely out. It almost looks like a cleavage plane. Hopefully, it doesn't part there. But, it is vertical. It will be vertical to my table. It will be out the girdle of the stone, so it's probably not gonna show up, as long as it stays in one piece. I'll get most of it out, but there'll be still a little bit of that left.


I also spotted a little crystal in here that ... I hope that's out, because they don't heat. So, this is a disaster waiting to happen, but we hope we'll get through it. I'm gonna re-dop this up. We're now gonna be cutting a cushion that's not square, but still, hopefully, will be a beautiful stone.


Okay, I'm re-dopped once again, and I'm gonna work it, putting the shape in that's gonna, hopefully, remove most of the inclusion that's left. I have a little piece here that, once I put three facets down the sides or five, whichever I decide ... It's gonna remove that. I'm gonna work it, forming a nice girdle and, hopefully, getting rid of most of the inclusions. It will probably be a little bit left of the cleavage plane, but, like I say, it's gonna be right out of the girdle stone, and it's probably not gonna show up.


So, I have finished cutting this tanzanite using the Nubond 325, which is pretty much comparable to a 3,000 metal disk. I'm gonna polish directly from that. To do that, I'm gonna use a BATT lap. The BATT lap is a tin alloy lap that is harder than my tin lap and produces a nice flat facet. [inaudible 00:30:25] the BATT lap, we use WD-40 to clean it off. Then, we get our diamond powder. Get your finger a little greasy, so you pick up some diamond. This is 50,000 diamond, and we spread it across the lap evenly. Now, you're ready to start polishing. I generally run middle speeds on this, anywhere from slow to fairly high speed. I'm gonna start with the ... I've got three rows of step facets at 60 degrees, 51 degrees and 41 degrees. I'm gonna start at the 60 degree, because I've got a little bit of inclusion I want to get out. So, I'm gonna polish until I remove it.


Up to now, while cutting, I used a visor. Visor's much quicker to use than using a loupe, but once you start polishing you're gonna need to move to the loupe, so you can see much closer. I'm making minor adjustments, trying to get back to where I'm polishing the entire facet. This has got just a teeny bit of my imperfection left, so I'm gonna polish a little bit deeper. You don't want to have to polish too far, because you're gonna have to do that to all the other facets. If you have to go too far, you may as well go around and recut rather than try to polish something off. This particular inclusion is very small and it does break the surface, so it shouldn't cause any issues with heat, but better gone than there. That's pretty much got a nice polish on that facet.

                                                [inaudible 00:34:38] polish facet. When I'm talking about the difference between light and dark is when ... That transition between a bright reflection to a dark reflection is where you're gonna see the facet the best. You can see this facet is, hopefully, pretty well polished, not wiped off pretty well, but it does have a good polish on it, smooth, no dots. It's ready to go onto the next facet.

                                                I've finished cutting the pavilion now. I've got three rows of step facets that are at 41, 51, and 60 degrees. Now, we're gonna take it from the machine, and we're gonna transfer it into a V-dop. We're start cutting the crown after the glue dries.

                                                So, it's time to remove our dop from the crown side of the tanzanite. This is where I've had problems before. I didn't dop, put glue underneath the dop, but because of the way it formed to the top of the stone, there will be some glue underneath it, so I will have to heat the dop. This shouldn't be an issue, but, as I've said before, it's been an issue before with a stone that looked much like this.

                                                So, I've got most of the glue picked off of this. You do have to be careful when you're doing this. I want to get as much off as I can. But, when you're popping it out, you can pop a little chips off your stone. So, just be cautious. And then, once most of it's off, I try and go around the edge of the dop quickly and just get as through as much off that as possible. Sometimes, it will pop off, but, I think, in this area, I've got glue underneath it, so we're gonna have to heat the dop. Just put the dop over the flame, hold the stone tightly, putting pressure on the ... Sometimes, it pops off that easily, but try and hold on to the stone. So, we're freed and ready to cut the crown of the stone.

                                                Now that we've freed up the crown side of the stone ... As I told, my cutters, the first thing you have to go after is the problems. This stone has a problem: the angle here is gonna determine what the angle that we're gonna cut the girdle at ... To do that, I usually put it down on the lap, try and get the light in the appropriate position, find out where that's at, and try and visually see what's flat. Not too easy to do. After that, we'll cut a little bit and see just where we're at. This is set at 46 degrees, which is pretty low for the culet angle, but it's what we have to work with.

                                                Still cutting through the glue that was there. [inaudible 00:40:40] set it up a little bit higher, like to get as much height to this first facet as possible, because the lower we cut it, we cut away a lot of the material that's on the rest of the stone. This is the low point that we have to deal with. The rest of the stone ... There's plenty of material. We'd like to keep as much of that as possible by getting this angle up as high as possible. It looks like 55 degrees is about where we're gonna be, which is good. That's a good starting point. So, we'll try to do something like 55, 40, 30, or 35 for the three facets. I'm gonna do a step cut crown. That's formed our girdle, and we are at 55 degrees. I'll finish the step facets around that 55 degrees, and then we'll go on to the next raw facets.

                                                When you start cutting the girdle, you want to take a close look at the facet and try and determine whether it's completely square. As you go around and cut the entire girdle, if this isn't completely rectangular and parallel sides, what's gonna happen is when you get back around to this facet, the girdles are not gonna match. So, try and make it as square as possible, and if it doesn't match up, you go ahead and feather back around and try and get everything to match up correctly.

                                                This is an issue you're gonna run into often, and that's once you get around [inaudible 00:43:45] you get around to where you started and you don't quite match. So, your options are: recut all the facets ... In this case, I don't have a lot of girdle left to [inaudible 00:43:57] ... or you can feather them in, and that means going from this facet to the next facet and just making them closer but not perfect. So, this next facet I would cut until it almost meets at the girdle and then go on to the next one and just feather the end to get them as close as possible.

                                                Normally, this should be at zero. We normally start the lowest facet and set the gauge to zero, but, because we started at the problem and it was on the end, which is actually the highest point, and I used zero there, once I get around to the thinner edge of the stone, my gauge is gonna be under zero. It's not a problem, because we're well above critical angle. When you go to polish, just remember where you started. Remember that, in this case, I was on the end, and I set to zero. So, if you start polishing on the end and set it to zero, everything's gonna work out okay.

                I have finished the stone ... not quite as big as I'd hoped for, but inclusions were definitely a problem. I'd hoped for 30 carat, but maybe we're in the 20-carat range.

It's a fairly deep step cut, so I'm hoping tomorrow to take that out of the jar, and we hit at least 20 carat, and I get to still make some money. So, take it out of the machine, put it into a jar of attack, and by tomorrow it should be free. We'll weigh it up and get ready for heating, and then we'll move on to the next half of the stone.

                                                This stone, I've decided to cut it down the blue axis. It's gonna be a deep stone. Some people might not like it, because of the depth, but it needs a lot of help color-wise, as half the crystal didn't have a lot of color. So, I'm gonna cut it right on the blue and hope to get a 10-carat stone. It will be a little overly deep, but we can design a pendant for it ... Christopher Michael design something and build it in such a way you can't see the depth. But, that extra depth is gonna add to the color of the stone, and, because we cut it in a step emerald cut, it should also add to the depth of [inaudible 00:47:26]

                                                21 ... Well, it's time to put our stones in the oven, and tomorrow we'll find out whether it's a bad day or a good day, because ... Here's our stones, we have a 16 carat and a 21 carat. Now, the 21 carat has a little very teeny crystalline inclusion down near the culet of the stone. And crystalline inclusions can be issues. It can cause fracturing. So, what I'm gonna do, I'm gonna heat very slowly, I'm gonna take 24 hours to go up to 1,050 degrees. Hopefully, the slow rate will prevent the expansion of that crystal to create a fracture in the stone.

                                                I'm gonna put them in my vessel and cover them with investment. This is to slow the process of heating. Cover it up and into the oven it goes. This is gonna take about 24 hours to finish this process. Usually, I do it in about 10 hours, but, hopefully, it will be successful and won't have an issue tomorrow. The oven is set and started. It looks like 24 hours and 15 minutes before I can open that oven back up.

                                                We've removed our stones from the oven. They've been in for 24 hours, about twice what I'd normally do, but it's all because of my fear of this stone cracking. It has a few issues inside one of them. As I've noted all the way along this video, I've been a little bit nervous about this particular piece. So, we heated it slow over 24 hours, and it cooled over the last 12 hours. Now, it's time to see what we've got. The risks here are ... The one stone that's included that I'm worried about weighs 21 carats. Even at 400 dollars a carat, we're looking at an 8,000-dollar stone, so that's the risk at the moment.

                                                All right, let's see what we've got. This is the 16-carat emerald cut, lighter color as I expected. Doesn't look like any issues. Kind of a light salon color. Track this down. It looks clean, success! And a really pretty purple color, not the most intense color, but a beautiful stone, good brilliance. What a relief, no cracks. So, we've got a 21 carat that's a little more purple, little deeper color, and a 16 carat emerald cut. So, 37 carats total weight out of our 112 carat tanzanite rough. No cracks and just very attractive stones. So, I would put this at ... Maybe this one 400, 450 a carat; maybe this one somewhere in the 300 a carat price.