On The Fly

In this episode, Mr. GIA . . . Can you name one person who, during your lifetime, changed the course of your life in an extraordinary way? Was it a parent, a teacher, a historical figure, or maybe a serendipitous acquaintance? One person stands out among all others -  Richard T. Liddicoat .  Sunday, March 2, 2025, would have been Mr. Liddicoat’s 107th birthday. Although he passed away in 2002, his memory lives on in me. In 1985, as a resident student at The Gemological Institute of America (GIA) in Santa Monica, CA, I was invited by Richard T. Liddicoat Jr. (then Chairman of the Board) to his office. As a student of human nature, lover of gems, and lifetime GIA advocate, he would visit every Resident (on campus) Colored Stone/Gem Identification classroom just before each class was to graduate. He would often bring samples of unique gem materials submitted to the GIA Gem Trade Laboratory for the students to see. Or he would simply stop by a classroom to discuss industry tren...

Over the course of a career teaching gemology, students have asked me many questions that gemologists tend to take for granted. This hit home recently at a writers group meeting when I casually used the term refractive index in one of my fictional works and the question immediately came up, “What is refractive index?” This brief column is devoted to you, the curious student. It is an opportunity to ask anything you ever wanted to know about gemology (within reason) but were afraid to ask. So let’s begin. What does refractive index (R.I.) mean? Gem-A Refractometer The amount to which a gem slows light is called its refractive index (R.I.). R.I. is calculated by the ratio of the speed of light in air to its speed in a gem. It is one of the measurable properties that gemologists use to assist with a gemstone’s identification.  For example, using your smartphone or computer, go to the computational database WolframAlpha . Type in “What is the speed of light in air?...

Peridot: Photo Robert Weldon Gemstones have been my fascination since childhood and, although in 1985 I embarked on the study of gems, I could never get a handle on practical gemology until I met Hercule Peridot. My name is Adamas Bontemps; as you will see, I was destined to discover the power of that elusive skill, the science of deduction. That cold, windy February day in Chicago would change my life forever . . .  It was 1982 when I first met Peridot; he was on the docket as the primary lecturer for a weekend gem seminar at the Natural History Museum in Chicago. It was a three-day affair. Peridot’s expertise was diamonds; in his flamboyant, jocular style, he captivated the audience with the power of the spoken word. The history, lore, the remarkable properties, and most of all, his enthusiasm and love for the study of that elusive gem. Day two of the conference, it was as if my mind was radiated by a glowing light, “That’s exactly what I want to do!” That day was ma...