The Gemological Institute of America (GIA) has launched an expanded method of evaluating nacre on all of its pearl classification reports, which it believes will improve the description and better serve clients.
Previously, the GIA classified nacre as “acceptable” or “unacceptable.” It used “acceptable” to indicate expected commercial nacre quality in terms of thickness, layering and condition, while “unacceptable” described those of poor quality, with features such as thinness, chalkiness or damage, the GIA said Monday.
The GIA’s new scale, which examines differences in nacre layering and continuity during a pearl’s growth, will primarily class pearls as having “good,” rather than “acceptable” nacre. The institute will evaluate the pearl’s nacre based on the degree of eye-visible movement found on either the surface or subsurface layers of nacre, in addition to the post-harvest condition, which includes wear, damage, modifications and treatments, as well as trade standards for thickness.
GIA will now use one of five different classifications ranges for each pearl: excellent, very good, good, fair and poor. It will state these new categories on all of its pearl reports.
“Nacre formation plays a critical role during a pearl’s growth, as its structure influences other value factors such as size, shape, luster, and surface quality,” said Tom Moses, executive vice president and chief laboratory and research officer at the GIA. “Nacre thickness and continuity also affect the pearl’s durability. This update on the nacre quality scale provides improvement to the existing nacre quality description for the GIA 7 Pearl Value Factors classification system that better serves our clients.”
Image: A GIA pearl report. (Gemological Institute of America)
