Lab Offers “Blue-White” Designation

The Professional Gem Sciences (PGS) gem grading laboratory in Chicago wants to use the term "blue-white" on its grading reports for D or E colorless diamonds that have "very strong blue" fluorescence. "Blue-white" hasn't been used for decades because the Federal Trade Commission says it's unfair practice to use the term unless a diamond shows blue or bluish color. PGS appears to be challenging that ruling, since the body color of a diamond receiving the blue-white grade is colorless. To prevent an FTC challenge, PGS says it will place the new grade in a category called "Color Appearance," which will include a Munsell color notation. (Munsell is a standard descriptive color system.) Colorless diamonds with very strong blue fluorescence often do appear bluish in daylight. Some diamonds with very strong blue fluorescence have been described as appearing "cloudy" or "oily" in daylight be

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