During his more than 50 years of involvement with the GIA Gem Laboratory, G. Robert (Bob) Crowningshield has made many significant contributions to the study of gems and the science of gemology. These include fundamental advances in the understanding and identification of treated and synthetic diamonds; of colored stones such as tanzanite, amethyst, “padparadscha” sapphire, and heat-treated corundum; and of natural and cultured pearls. In the early 1950s, Crowningshield demonstrated the value of new equipment in gem testing, in particular the spectroscope. He also helped develop and teach the GIA diamond grading system, now the standard worldwide. Along the way, he shared his wealth of practical experience in hundreds of articles, lectures, and industry presentations. All of these achievements helped lay the foundation of modern gemological research.

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