Dr. James Shigley, the Gemological Institute of America’s distinguished research fellow, gave two presentations on diamond gemology to the Prospectors and Developers Association of Canada’s 2009 convention in Toronto last week.

The event, PDAC 2009, is an international opportunity for exploration companies, mining organizations, investors, government agencies, and non-governmental organizations to meet each year to focus on exploration and the world’s mining and minerals industries. More than 18,000 attendees from 52 countries, including Brazil, Chile, China, Greenland, Africa, Mongolia, and New Zealand, attended.

“Our convention topics normally cover mineral exploration and mining,” said Patricia Sheahan, a member of the PDAC Convention Committee. “Dr. Shigley made the first presentation ever to our group about diamonds and their properties as a gemstone. It was an eye-opening experience.”

Shigley was asked to present two 25-minute lectures on diamonds: one on colored diamonds and one on synthetic and treated diamonds. An estimated 400 people attended each presentation.

Shigley summarized the causes of color in a diamond, famous colored diamonds, colored diamond prices, geographic sources, and manufacturing for jewelry use. He also explained the basic concepts behind color grading and quality evaluation of colored diamonds provided by the GIA Laboratory.

Shigley’s second talk on synthetic diamonds and treated diamonds summarized some ideas on their gemological identification. He explained the background and functional aspects of producing synthetic diamonds. Both categories of gem material are present in the marketplace, and can present problems for jewelers in terms of proper information disclosure about their identity.

JCK