Joined: Fri Feb 24, 2006 1:20 am Posts: 2756 Location: Southern California, U.S.A.
I reallly AM asking for a friend: if a synthetic boule of star corundum is cut concavely, will it star? The notion seems to tickle a memory buried deep in my brain that says "yes." It seems logical to me that if the silk is distributed evenly through the boule a star should be evident both convexly and concavely if the boule is oriented properly. Opinions? Thoughts? Thanks.
Joined: Tue Apr 05, 2016 7:58 pm Posts: 1424 Location: San Marcos, CA
ROM wrote:
I reallly AM asking for a friend: if a synthetic boule of star corundum is cut concavely, will it star? The notion seems to tickle a memory buried deep in my brain that says "yes." It seems logical to me that if the silk is distributed evenly through the boule a star should be evident both convexly and concavely if the boule is oriented properly. Opinions? Thoughts? Thanks.
What do you mean exactly cut concavely? In the sense of a cabochon or a concave faceted stone or other?
Joined: Tue Apr 05, 2016 7:58 pm Posts: 1424 Location: San Marcos, CA
As a 3d Rendering I get that, is that what you mentioned at the Idaho shop? So in theory lets take, say a 12mm Round high dome cabochon. It has a star and all is orientated correctly, we take 10mm Round nose set of diamond bits and create the polished concave as your rendering, we will or maybe will have a star of similarity as the convex cab had?
Joined: Fri Jun 25, 2010 12:04 am Posts: 257 Location: Idaho
Here you go. Don't need sleep anyway...
Brazilian 4-ray star garnet, had polished the top top locate/orient the star but never finished cutting this piece...
First is a top picture of the convex polished "cab" and star.
Second is a picture of the bottom of the piece. I cut two 4 mm cups in to the surface with a diamond ball burr, then gave it a quick (sort of) pre-polish with 3,000 diamond on brass. Then a little WDE 40 to give it a better shine. It is just a quick and crude experiment/proof of concept, after all!
Pictures taken with my iphone, using its flash to show the star.
Attachments:
File comment: Quicky orientation surface on a piece of Brazilian 4-ray star garnet.
Braz 4-Ray Star top (460x600).jpg [ 226.31 KiB | Viewed 2178 times ]
File comment: Two roughly polished concave surfaces showing 4-ray stars, in back of piece.
Braz 4-Ray Star Conc 1 (464x600).jpg [ 242.82 KiB | Viewed 2178 times ]
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