Eduard Guebelin, 91; Gemologist Explored Beauty of Flawed Stones

Eduard Guebelin, 91, who demonstrated that “inclusions” that were once considered undesirable flaws can indicate the origins of diamonds and other precious stones, died March 15 in Lucerne, Switzerland, of natural causes.

Born to a Swiss watch-making family in Lucerne, Guebelin studied at the University of Zurich and earned a doctorate in mineralogy from the University of Vienna. In 1939, he also received a diploma from the Gemological Institute of America in Los Angeles, which publishes the quarterly journal Gems & Gemology.

Guebelin published widely and in 1953 issued a report that provided, according to Gems & Gemology, “the first systematic classification of inclusions in diamonds, colored stones and synthetic gem materials.”

Before Guebelin’s work, the journal noted in a 2003 tribute, “inclusions in gems were generally considered disagreeable ‘flaws’ or ‘imperfections.... ‘ Today, however, gemologists almost instinctively recognize the diagnostic importance and natural beauty of inclusions.”