The American Gem Society honors the life and legacy of Peter Yantzer, ECG—a remarkable leader, gemologist, and friend whose work helped change how we see diamond beauty.
Peter passed away on January 10, 2026, and leaves behind two daughters, Melissa and Elise, his grandchildren, and his brothers, Paul, Phil, John, and Steve.
Peter’s loss is felt deeply by all who knew him and by the many whose lives and careers he touched through his warmth, humor, and dedication to excellence.
Peter joined AGS Laboratories in 1995 as Executive Director, bringing with him vast knowledge and a deep belief that the science behind diamond grading could serve both the jeweler and the consumer. He helped build AGS Laboratories from the ground up, establishing a team, a reputation, and a standard of excellence that would become the Lab’s foundation.
His vision led to one of the greatest advancements in diamond grading, the AGS Light Performance Cut Grade System. Peter and his team spent five years studying how light interacts with a diamond, working alongside optical physicists, mathematicians, and industry experts. Peter’s contribution helped shift the focus of diamond grading from what could be seen on paper to how a diamond radiates brilliance, fire, and sparkle.
Before his time with AGS, Peter began his gemological career with the Gemological Institute of America in 1972, where he served as a staff gemologist, instructor, and later, director. Throughout his career, he was known not only for his expertise but for his patience, kindness, and willingness to mentor others.
In recognition of his extraordinary service and impact on the science of gemology, Peter received the Robert M. Shipley Award® in 2005—one of AGS’s highest honors. His contributions strengthened the bridge between artistry and science, helping elevate the entire jewelry industry.
“Peter’s contributions to AGS and the industry are vast and have profoundly influenced the course of diamond grading. We are deeply grateful for his leadership of AGS Laboratories and the lasting impact he made on the AGS community,” said Katherine Bodoh, CEO of the American Gem Society. “We will especially miss his warm smile, quick wit, and genuine love of life.”
Peter retired from AGS Laboratories in 2015, leaving behind a legacy of innovation and integrity. The American Gem Society is forever grateful for the work, leadership, and life of Peter Yantzer. He is survived by his four brothers—Steve, John, Paul, and Phil—his daughters, Melissa (and her husband, Chad) and Elise, and his grandchildren—Tyler, Kendall, Brayden, Kaleb, Logan, Ryder, and Julia.