Faceting Focus: Captivated by Peridot

cut brilliant peridot
Complete round cut brilliant peridot by Jim Perkins. (MARK OROS, Hashnu Stones & Gems, www.hashnustones.com)

By Antoinette Rahn

The round brilliant design illustrated and outlined in this article was created by Jim Perkins, specifically with peridot in mind. During the process of creating this particular design, Perkins came away with new realizations about the faceting process, stone, and himself.

“I like good brilliance and contrast with no extinction and no table reflection. However, optics is a matter of choosing your priorities and trade-offs. Sometimes you must give up something in order to make gains in other areas. That was especially true during the process of optimizing this design,” explained Perkins, whose fascination with rocks, gems, and minerals began in the fourth grade.

Reflection Acceptance

The brilliance and contrast he sought were achieved, he added. However, it required Perkins to accept a slight table reflection. Although this is something physicists and fellow gem designers have said is common and nothing to worry about, Perkins says that’s easier said than done. Yet, in this case, once he accepted the reflection, he was able to see that the gem fractures the light in a most satisfying way, he said.

Feedback from other designers, gem cutters, and connoisseurs about this design has been nothing but positive, which, Perkins said, reminds him to accept compliments and trust in the opinions of knowledgeable friends.

“I am fortunate to have a great bunch of long distant colleagues I can ask to give their opinions, and I can count on them to tell me the truth, whether I like it or not,” he said.

As with most faceting projects, there are key factors to keep in mind. Upon our request, Perkins identified the three most valuable things to keep in mind when cutting peridot.

3 Keys to Cutting Peridot

1. Peridot is difficult to evaluate for inclusions. You can pick a piece you think is clean, and after cutting and polishing you will find inclusions.

2. Some of the cleanest peridot seems to come from Pakistan and China. Although, I also like Arizona peridot.

3. Polishing can be difficult. Most cutters say to polish with aluminum oxide. However, I have the best luck with a BATT LAP with 3,000 diamond for pre-polishing and another BATT LAP with 100,000 diamond. I use paraffin-based candle oil as a lubricant for both BATT laps.

When asked why he chose the round cut brilliant design for this peridot and the origins of this design, Perkins shared a bit about the general history of the round brilliant cut, as well as his early experience faceting.

History of Techniques

By various accounts the development of the round brilliant cut is the result of an evolution of techniques and the mathematical formulation of Marcel Tolkowsky, the author of the revolutionary reference Diamond Design, Perkins explained.

Over the years, cutters of colored gems derived their cutting angles by extrapolating them from diamond cutters and the refractive index of material they wanted to cut, he further explained.

Perkins’ first exposure to gemstone cutting and design came when he was in seventh grade, during a meeting of the Akron, Ohio Gem & Mineral Club and The Medina Gem & Mineral Society, of which his family belonged. A man by the name of George Morse had built his own machinery, drew diagrams by hand, and cut quartz gems.

“When I saw what he could do, I was hooked on faceting,” said Perkins, who immediately asked his parents for a machine to begin faceting work. However, it wouldn’t be until the early 1990s before Perkins purchased his own equipment and got down to work.

“I struggled to learn the [cutting] technique from my teacher and after I completed my first round cut brilliant, he told me to ‘go home and cut 25 more stones then bring them back and I’ll show you what you did wrong,’” Perkins said. “I looked at my stone and thought, this is pretty but there is something wrong optically. Over the years I would study in my spare time reading what I could. Eventually, I went to school at the lapidary school in Young-Harris Georgia.”

For the last nearly 30 years he’s been honing his craft and enjoying related exploration, achievement, an opportunity to share what he’s learned. One of the most beautiful aspects, as Perkins demonstrates, is the chance to always be learning.

Faceting Instructions