GIA's Head of Quality Assurance Gives Speech on Colored Stones

His lecture came at the end of the second day of the Buyers Week, and dealt with one of the hottest topics in the industry: fancy shape colored diamonds and their prices which have continuously risen in recent years.

Attendees of the second US & International Diamond Week at the Israel Diamond Exchange heard a presentation from John King, GIA’s (Gemological Institute of America) chief quality officer and noted expert on colored diamonds on the GIA's colored diamonds grading system.
 
King singled out several reasons for the rising prices, including technology and polishing styles, new mines and the move to underground mining at the Argyle mine in Australia – the main source of colored diamonds, the marketing strategies for these stones and diamond tenders.

"In addition to these factors that have influenced prices, we have noticed at the GIA a rise in demand for our grading services as well as for the range of colors and sizes of these diamonds," King said. Since 1980, demand for colored diamonds has been increasing.

Much of King's presentation dealt with understanding the color element as a factor in determining the price as compared with the other three Cs of carat, clarity and cut.

"The way the human brain absorbs in reality is a leading factor. So when we come to grade the diamond we neutralize factors that influence how we see the color such as the source of light and type of lighting, and also take into account factors such as color memory, the size of the stone, the type of polish and other elements."

King explained how the GIA's grading system for such diamonds works, the differences between grading reports, and showed members of the audience the differences that can be seen by the naked eye between yellow diamonds with the same grading but with a different polish.

He also spoke about the high prices of colored diamonds at auctions around the world in recent years, and in particular the pink diamond bought by British jeweler Laurence Graff for $45 million.

"Despite their popularity, colored diamonds accounted for just 3 percent of the diamonds sent to the GIA for grading," he concluded.