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GIA Introduces Expanded Nacre Scale in Pearl Classification Reports May 26, 2025 (0 comments)
New York, NY--The Gemological Institute of America (GIA) has updated its pearl classification system by introducing a five-tiered nacre scale in all pearl reports. The change expands on GIA’s 7 Pearl Value Factors: Size, Shape, Color, Nacre, Luster, Surface, and Matching.
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GIA previously classified nacre as “Acceptable” or “Unacceptable” based on thickness, layering, and condition. The new system, developed after input from the global pearl trade and examination of diverse pearl samples, replaces the binary model with five grades: Excellent, Very Good, Good, Fair, and Poor.
The report noted that most pearls will now be classified as having “Good” nacre, reflecting the typical commercial quality in the trade. Nacre assessments consider visual variation in surface and sub-surface layers, post-harvest wear, damage, treatments, and standard thickness requirements.
Tom Moses, GIA’s executive vice president and chief laboratory and research officer, said nacre quality impacts other pearl value factors like size, shape, luster, and surface, and affects durability.
A sample GIA Cultured Pearl Classification Report, #2233514599, showing the new scale, is available through the GIA Report Check service. GIA has been classifying pearls since 1949 and has contributed to industry standards, including revisions to the U.S. Federal Trade Commission’s pearl guidelines.
Check out the news release here.