Gems & Gemology mourns the loss of “Pete” Yantzer (see above), who passed away on January 10, 2026, at the age of 77. A gemologist, educator, and visionary leader at both GIA’s and the American Gem Society’s (AGS) diamond grading laboratories, Yantzer will be missed by his many friends in the trade.
Unsure of a career path after serving in the U.S. Air Force, Yantzer was told by a family friend in the jewelry industry that gemology was a fine career choice, so he enrolled at GIA using his GI Bill. After graduation, Yantzer joined the Institute in 1973 to become the New York Gem Trade Laboratory’s seventh staff gemologist. He always expressed his good fortune to be mentored by some of the true giants of gemology—Richard Liddicoat and Robert Crowningshield. By 1976, he was leading GIA’s newly established Los Angeles lab. There, he steered the rapid expansion of GIA’s diamond grading services during the diamond “investment” boom of the late 1970s.
After a break from the trade, Yantzer became the first executive director of the AGS diamond grading laboratory in 1996. Over the next five years, he worked tirelessly with a team of optical scientists, mathematicians, and industry professionals to develop the AGS Light Performance Cut Grade System. At the heart of this project was Yantzer’s conviction that cut grading was the most important factor in a diamond’s beauty. During his time at AGS, Yantzer mentored the next generation of diamond cut researchers, several of whom continue to advance the practice of cut grading at GIA following the acquisition of the AGS laboratory in 2022.
Yantzer’s decades of leadership and intellectual curiosity elevated the practice of diamond grading and guided the industry toward cutting standards that produced more attractive diamonds for consumers. Because of his lifelong contribution to the practice and science of diamond grading, Yantzer was the 2005 recipient of AGS’s Robert M. Shipley Award, its highest honor.
Yantzer is survived by two daughters, seven grandchildren, and brothers, Steve, John, Paul, and Phil. We extend our sincere condolences to his family and friends.
Gems & Gemology mourns the loss of “Pete” Yantzer (see above), who passed away on January 10, 2026, at the age of 77. A gemologist, educator, and visionary leader at both GIA’s and the American Gem Society’s (AGS) diamond grading laboratories, Yantzer will be missed by his many friends in the trade.
Unsure of a career path after serving in the U.S. Air Force, Yantzer was told by a family friend in the jewelry industry that gemology was a fine career choice, so he enrolled at GIA using his GI Bill. After graduation, Yantzer joined the Institute in 1973 to become the New York Gem Trade Laboratory’s seventh staff gemologist. He always expressed his good fortune to be mentored by some of the true giants of gemology—Richard Liddicoat and Robert Crowningshield. By 1976, he was leading GIA’s newly established Los Angeles lab. There, he steered the rapid expansion of GIA’s diamond grading services during the diamond “investment” boom of the late 1970s.
After a break from the trade, Yantzer became the first executive director of the AGS diamond grading laboratory in 1996. Over the next five years, he worked tirelessly with a team of optical scientists, mathematicians, and industry professionals to develop the AGS Light Performance Cut Grade System. At the heart of this project was Yantzer’s conviction that cut grading was the most important factor in a diamond’s beauty. During his time at AGS, Yantzer mentored the next generation of diamond cut researchers, several of whom continue to advance the practice of cut grading at GIA following the acquisition of the AGS laboratory in 2022.
Yantzer’s decades of leadership and intellectual curiosity elevated the practice of diamond grading and guided the industry toward cutting standards that produced more attractive diamonds for consumers. Because of his lifelong contribution to the practice and science of diamond grading, Yantzer was the 2005 recipient of AGS’s Robert M. Shipley Award, its highest honor.
Yantzer is survived by two daughters, seven grandchildren, and brothers, Steve, John, Paul, and Phil. We extend our sincere condolences to his family and friends.
