Diamond Portraits: G. Robert Crowningshield

George Robert Crowningshield may not be a household name to many in the diamond industry, however he is responsible for a number of important discoveries that impact nearly everyone in the trade. Key among them were techniques in detecting diamond fraud. He was also instrumental in establishing what are known as the 4Cs.

Born in Colorado Springs, Colorado in 1919, he earned his bachelor degree in natural sciences from San Diego State University and then joined the navy, where he served as a naval officer during World War II. After the war, he joined Gemological Institute of America (GIA) as an instructor in Los Angeles.

In 1949, Crowningshield was sent to New York City to set up an East coast office and laboratory for the institute and, in 1950, he was named director of the New York office. He then embarked on a scientific journey that led to thousands of groundbreaking innovations and discoveries that would take GIA and the field of diamond gemology to new heights.

One of his first important discoveries was in 1956, when he figured out how to detect yellow irradiated diamonds with a spectroscope. At the time, there was a sudden surge in the number of yellow diamonds appearing on the market. With concerns over the authenticity of these diamonds, an examination under a microscope did not reveal anything suspicious about them.

Though the spectroscope was rarely used by the diamond industry, Crowningshield examined every gemstone submitted to GIA, drawing the absorption patterns with charcoal on paper. By examining the spectra of more than 10,000 natural-color and irradiated yellow diamonds, Crowningshield spotted the 592 nm absorption line that indicated irradiation treatment. With this discovery, he established the spectroscope as an invaluable tool in gem identification, among others, to assess the authenticity of color in a diamond. His illustrations became a regular resource in gem identification. 

Another important contribution Crowningshield made was that of the 4Cs. Together with others in GIA, he took the recently established color grade of diamonds that was developed by Richard T. Liddicoat , and together with the clarity grading system, he created a standardized approach to assessing diamonds that could be easily marketed to consumers, helping them better understand the pricing differences in diamonds.

In 1970, Crowningshield discovered a new laser drilling process used to bleach dark inclusions in diamonds. When General Electric announced in 1971 the development of an HPHT gem-quality synthetic diamond, Crowningshield wrote the first scientific study of the material.

His research was not limited to diamonds, but extended to pearls, sapphires and other precious gems. He frequently wrote and lectured on his findings to help spread the knowledge to others and help them with their work in the industry.

Crowningshield’s work did not go unrecognized. He was the recipient of several prestigious awards including the American Gem Society's Robert M. Shipley Award, Modern Jeweler's Lifetime Achievement Award, and the American Gem Society Lifetime Achievement Award. In 1997, when he retired as vice president of its laboratories, GIA named its research facility the G. Robert Crowningshield Gemological Research Laboratory.

G. Robert Crowningshield died on November 8, 2006 in Hightstown, New Jersey. He was 87. 


(Picture: Gemological Institute of America)