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Thomas Gelb began his career in gemology in 1993 after graduating from the University of Massachusetts, Amherst with a degree in economics. He spent the close to 15 years at the Gemological Institute of America, the industry leader in diamond grading and evaluation. Starting as a diamond grader he learned about diamonds and their properties. Within one year he started to focus on fancy colored diamonds, first evaluating their color and then determining the origin of that color. In 1996 when the Smithsonian wanted an evaluation of the Hope diamond Gelb was one of four gemologists assigned to the task. During his time at the GIA he was able to work with some of the legends of gemology including Bob Crowningshield, Tom Moses, and Wuyi Wang.

In 2005 Gelb became the manager of the colored diamond department in New York, responsible for the quality and flow of every fancy colored diamond submitted. In his time there he evaluated some of the most famous diamonds in the world, including the Hope, the Idol’s Eye, the Agra, the Allnat, the Incomparable, the Steinmetz Pink, the Moussaiff Red to name but a few.

One of his additional responsibilities at the GIA was as one of only two gemologists (the other is Tom Moses GIA’s current Laboratory head) to work on damage reports for insurance purposes. The goal of these reports was to evaluate diamonds that had been claimed to have been damaged to assess, if possible, when and how that damage occurred. He is one of the few people in the world trained by the GIA for such work, and is a subject matter expert.

Gelb left GIA in 2008 to run the grading department of Harry Winston (a leading high-end luxury retailer). His work there consisted in both evaluating and running the department that evaluated all the gems in HW jewelry for quality. While there he had the opportunity to further refine his knowledge of both diamonds and the jewelry industry at large.

Gelb has continued his education throughout his career. He earned a graduate gemologist degree from the GIA in 1996. His course work included diamonds, diamond grading, colored stones, colored stone grading and gem identification. He has also completed a gold and precious metal course through the GIA. In addition to his gemological education Gelb earned an MBA from Columbia Business School in New York in 2009. His coursework was broad based in all facets of business with a concentration on operations management and strategy. Many of his projects were diamond industry related such as a diamond pricing analysis, diamond auction strategies, inventory management, potential diamond investment derivative markets, and jewelry industry strategy.

Armed with his new business degree and 15 years of gemological knowledge Gelb left Harry Winston in 2009 to launch Gelb Gemological Consulting which provides business and gemological consulting to the jewelry trade. Through this firm he has worked on numerous and varying projects with a wide array of clients. His work has included training laboratories and diamond manufacturers in diamond grading, evaluating many thousands of diamond for potential quality improvements, working with some of the largest firms in the colored diamond industry to improve the value of their diamonds, advising a diamond investment group on the development of their diamond related fund offerings.

In 2012 Gelb accepted the position of Educational Director of the Natural Color Diamond Association. His responsibilities include coordinating, writing and editing all of the educational materials of the leading colored diamond trade organization. He also gives seminars on natural color diamonds and advises membership on their color diamonds.

Gelb is an award winning author of numerous articles on diamonds, ranging from treatment and synthetic criteria to comprehensive articles about specific colors of diamonds. His work has been seen most often in Gems & Gemology (the leading gemological reference periodical) and Natural Colors (the quarterly publication of the Natural Color Diamond Association.

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Northampton MA 01060
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