So with the closed material, or semi closed, you will always have 2 sides darker than the other 2 right(c axis sides)? And then the farther from center you make those sides the lighter the stone will be? (like a rectangle cut with the c ends as the small sides)
Dark stones look better with fewer, larger facets. Since the amount of color absorbed is directly related to the length of line the light travels inside the stone the goal is to shorten the line.
Do a simple step cut on both crown and pavilion. Sometimes it is best to let light leak. Transmitted light travels the shortest possible path.
Over time you will develop a library of cuts that work well for dark stones.
As I have said, you need a consistent way to evaluate your rough. I will have a new batch of light boxes finished next week.
Ok I'll start looking up ideas for step cuts, I'll get the cad software again also. I think the sim will help out rather than just guessing angles. Interested in the box for sure! I was thinking about the cut on the diaspore where 2 sides are pretty much just single cut large facets (c axis sides for the tourmaline) and then whatever on the other 2 (something fancy or flashy ab sides for tourmaline) just to give it some pop. Is this an idea that might work? The girdle is very thin on the 2 single cut sides I thought that would help as well.
here is a quick design I did for you for your long tourmaline crystals with a closed C axis. It opens up the A/B axis color while minimizing the dark ends from the closed C axis. It is a bit more interesting and brilliant than straight Emerald cut sides. Easy to cut as well.
I have included both an image rendering and the cutting diagram as a PDF file.
If you are going to start using CAD to design cuts, I recommend Gem Cut Studio. It replicated the cutting process very well, and is easy to learn.
Joined: Tue Apr 05, 2016 7:58 pm Posts: 1424 Location: San Marcos, CA
j.mcgee_1985 wrote:
I would like to see as well if I can!
So with the closed material, or semi closed, you will always have 2 sides darker than the other 2 right(c axis sides)? And then the farther from center you make those sides the lighter the stone will be? (like a rectangle cut with the c ends as the small sides)
Yes that is the correct understanding. If you look at the image of Steve's design the left and right ends are black the closed c-axis. The angles of the end facets are steepened to keep the dark from traversing into the open axis. In some cases they can be as steep as 75 more degrees, and can be challenging to cut and polish with long slender stone, hence where building a support in your dopping technics really comes in handy. Some machine manufacturers make specialized dops as well for these situations.
Here is a link to a video on the light box system I designed and built to evaluate rough and cut stones. It is a portable solution that gives me consistent and flexible light no matter where I am.
It works very well for me. I sell these to my students and it seems to help them a great deal with their purchases, and cutting. I don't want to violate any rules here on the forums about selling things. So if you are interested, PM me and I can give you more information.
. I sell these to my students and it seems to help them a great deal with their purchases, and cutting.
Let me know what you think of the tool.
I ordered one already, looks handy dandy Steve! What's this about students? How does one get lucky enough to be taught by such a knowledgeable and experienced individual?
Yes, I saw that you ordered one. You will get an email later today and the box will be in the mail tomorrow.
I teach Gemology and Gemstone Cutting here locally in live classes (Zoom since Covid-19). I also teach internationally and other remote students by Zoom. I enjoy teaching.
If you have questions or need advise on something please feel free to ask. I am always willing to help when I can.
Thanks Steve! That's awesome, I can't wait to try it out! I had family visit recently so I had been spending time with them but I have some updates I got the mdr machine! It came with a bunch of laps, I need help with a couple if you guys don't mind. Machine looks WAY better than the Graves. I have to remove it and re solder the power wires, 2 came loose. Will be working to get this together and set up today. The 10 gram stone came in as well while I was visiting with family, I'll take some measurements and post a couple pics of that later. Here are some pics of the laps and the machine. Nothing is clean or put together yet. Do you guys know what the cylinder next to the table adapter is? The drawers are all there, just out because they had stuff in them. Wax and powder/paste mostly.
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File comment: Not sure about these. 1 says #4000 hand engraved. The other stamped md&r 25. Steel I think. unknownlaps.jpg [ 95.02 KiB | Viewed 576 times ]
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