How GIA Identifies Colored Stones

Designs By Flora — Tue, 20 Mar 2012 19:36:29 +0000

GIA receives a varied and complex range of items for identification; everything from colored stones and pearls, unusual carvings and jewelry, to the latest in synthetics, and simulants, as well as treated gems. A significant area of activity involves the origin of color in gemstones, most notably, but far from limited to, diamonds, rubies, and sapphires.

Inspection, Care, and Handling Procedures

GIA applies the same item identification and tracking procedures to gem identification as it does to diamond grading. Each item is assigned a bar-coded label with a unique internal identification number that is used to track it throughout the process. And at every step, special inspection, care, and handling procedures serve to protect a gem’s identity and ensure it is managed with the utmost care.

Weights and Measures
This is the first stop for any gemstone. Loose gems are weighed with an electronic micro-balance that captures the weight to the fifth decimal place. Loose polished stones are also measured with an optical measuring device to determine their proportions, measurements and facet angles. Mounted stones are measured, but not weighed.

Identification
Items are then transferred to the Identification Inventory Control department for distribution to trained and experienced gemologists for servicing. Once an item is received by an initial gemologist, its recorded weight and measurements are verified, or if the item is mounted or strung, the gemologist will use manual measuring devices to determine and record necessary measurements.

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