Category: Preforming

Preforming: What’s The Best Way?

by Fred Van Sant With the new bells and whistles added onto faceting machines in recent years, preforming options have expanded. It used to be that when you cut an octagon shape you always started with the dop arm at 90° and cut 8 facets using a positi …

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C.A.M. Preform: The Cone

by Fred Van Sant Instead of making the temporary culet point with the CAM facets, some cutters prefer to make rolled cone culet point first, then cut the CAM facets to It. They feel this assures them of starting out with a point that is centered on the …

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Best Index Numbers for Ovals

by Fred Van Sant How does one arrive at the best set of girdle index numbers when improvising or designing an oval with a faceted girdle? The most eye-pleasing shape is that which is as close as we can get to the perfect ellipse, but without a special …

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Be a Performer, Not a Preformer

by Glenn Klein What is all of this talk about preforming a piece of rough gem material? Why would you preform using a grinder? These and other suggestions are often made in descriptions on how to proceed to facet a gemstone. I see no benefit from prefo …

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