demantoid Barion cut - faceting stylesdemantoid Barion cut - faceting styles

Custom Gem Faceting Styles

Gem cutters can choose from many faceting styles. Learn about the most common custom cutting techniques and pick one that suits your needs and skill level.

6 Minute Read

Calibrated Gem Cutting Machines versus Jam Peg

Most custom cutters use calibrated machines. Every setting is precisely controlled. Factories, on the other hand, use simple “jam peg” machines for the majority of their cutting. Factory cutters attach a rough gem to a long peg, which is inserted, “jammed,” into a vertical plate with multiple holes. The holes give the cutter an approximate angle. Skill and experience determine the rotation.

Cutting with a jam peg machine requires great skill, but the work is never precise. Since the angle and location of a facet greatly affect the brilliance of the finished gem, this method usually produces less than ideal gems. Factories use it because of the minimal time required.

Calibrated machines take less skill to operate than a jam peg but give superior results. However, finishing a gem takes much longer. Nevertheless, the quality difference is so remarkable that new standards have been set for cutting colored stones. “Native cut” gems have almost disappeared from the market. Even some factories now offer gems cut with calibrated machines.

In this article, I’ll discuss faceting styles for use with calibrated machines. Jam peg cutting isn’t covered here.

Step and Brilliant Cuts

At the most…

Donald Clark, CSM IMG

The late Donald Clark, CSM founded the International Gem Society in 1998. Donald started in the gem and jewelry industry in 1976. He received his formal gemology training from the Gemological Institute of America (GIA) and the American Society of Gemcutters (ASG). The letters “CSM” after his name stood for Certified Supreme Master Gemcutter, a designation of Wykoff’s ASG which has often been referred to as the doctorate of gem cutting. The American Society of Gemcutters only had 54 people reach this level. Along with dozens of articles for leading trade magazines, Donald authored the book “Modern Faceting, the Easy Way.”

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