Getting the Best Yield from Crystal


Getting the Best Yield from Crystal

Here is an example using a very nice piece of rough Aquamarine I had for sale.

You should read this article… the example in it I use is this same crystal.

What rough can I make money on? How do I figure it out?

Item #: Large Aquamarine Crystal – $12/carat (2001)
Locality: Pakistan
Aquamarine CrystalAquamarine Crystal

I very seldom see Aquamarine crystal of this quality and size… This is good solid medium color blue and other than the growth line and little spot next to it, clean. The will cut some very large quality stones…

Sold:
1 each 186.0 carats – $2232.00 – blue/blue/green, best cut Barions – 26.5mm x 54.8mm x 11.2mm deep

Now that I have bought this crystal. How do I cut it up and get the best yield?

Examine the crystal very closely and take your time. No fast decisions. If you are not sure then think about it for as long as it takes. I sometimes think about a piece of rough for a long time. I had a Spinel (Ramp Cushion) that I thought about over a year before I cut it… I finally found the design the Spinel rough needed.
Graves faceting machine

On this piece of Aquamarine. It is quite good quality and will yield very high and in about any shape(s) you want.

However there are a lot of choices to be made and some of them depend on what the best yields would be and some choices are more about what you want to get out of the crystal and particularly what shapes.

I say shapes because I often may opt for a lower yield to get a shape and or design that I want or that I know will work especially well in this Aquamarine. Some shapes sell better than others too, and this is always a factor I consider. Shapes I usually try for are trillions, square cushions, cushions, and matched sets of about any type.

Above is a basic set of out lines that I would probably cut this crystal into… Keep reading I think you may see a few surprises on how I would approach this crystal. The first cut is obvious and it is to cut the crystal into two pieces along the fault line in the crystal slightly under 2/3rds of the way down.

Graves faceting machine

The main stone on the left side of this crystal is a trillion. I would use my “Signature #4” design, it is one of my favorites in Aquamarine.

Notice the flaw in the middle of the crystal where the line with the arrow starts (the smaller piece of crystal after you have cut it along the fault line, the right side, larger piece is clean after the crystal is cut in two pieces). What looks like a flaw below the arrowed line you can see in the picture, is actually the reflection of the actual flaw. It is not a flaw. This flaw (where the line with the arrow starts) is orientated and running at about 45 degrees towards the edge of the crystal. The edge of the crystal where the point of the pear is.

Graves faceting machine

If you look at the next picture (right) you will see that by cutting at a 45 degree angle with the saw blade (after cutting the crystal in two pieces) it will just about preform the the pavilion of the pear (on one side) and of course help point up the bottom of the trillion.

Note: I rotated the trillion a bit to get a long side along the saw cut.

Sawing at 45 degrees basically kills two birds with one stone. It creates pavilion points for both stones and removes the flaw that is/was present.

Note: I would use an ultra thin saw blade and I would trim the trillion on all three sides of the pavilion (the pear on the second side). The scraps from the trimming will not be large but I would guess there is several carats of cut stones in them when finished. The trimmings from the pavilion of the trillion could cut a couple carats each, depending on what design you use.

The table of the pear is actually on the bottom of this crystal in the picture (above), the opposite of the table for the trillion. Because of the 45 degree saw cut the pear will be quite a bit bigger, than if you just trimmed with the saw blade at 90 degrees.

Graves faceting machine

This one may surprise you. Notice in the top picture (above) I have 2 square cushions and two rectangles marked in on the right half of the original crystal. What you may not have guessed is how I would trim out the crystal and exactly where the pavilions of the stones will be.

Left: Is a picture of the end of the crystal. You will see that I would take a trim saw and cut at about 45 degrees through the middle of the length of the right piece of crystal.

The tables of these stones will be 4 o’clock and 10 o’clock respectively (12 o’clock would be at the top of your computer screen). The reason for doing this is that the stones will yield out much larger. But this is not an approach that a lot of faceters would think of, especially if they are not very experienced.

For the two rectangles I would consider my “Aqua Cisor” cut, and for the square cushions I would probably use my “Nigerian Cushion”. The “Aqua Cisor” has a keel and would really yield well in this material and the cushion is just a classic cut. I think that the over all yield cutting this crystal the way I have out lined would be quite good. I have picked designs that will help both with yields and improve color.

Take your time and think about the rough before doing any cutting and do not be afraid to be slow about cutting a piece of rough.

Gram Faceting Archive of Information
This edited version of an article by the late Jeff Graham is part of a special archived informational series from Gram Faceting. Used with permission.