Gemological Tools — How-To Guides

Reference guides for the instruments used in property-based gemstone identification. Each guide covers technique, calibration, and how to feed the reading into GemID.

Instrument Guides

Refractive Index

How to Use a Refractometer

Read refractive index from the shadow edge. Covers calibration, common errors, and interpreting doubly-refractive readings.

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Specific Gravity

How to Measure Specific Gravity

Hydrostatic weighing method. Equipment, the weighing formula, and how SG narrows candidates alongside RI.

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Chelsea Filter

How to Use a Chelsea Filter

Transmission filter for emeralds, rubies, tsavorites, and aquamarines. What red vs. green reactions mean — and when they mislead.

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UV Fluorescence

UV Fluorescence Testing

Longwave and shortwave fluorescence as diagnostic tools. Species-level patterns and treatment indicators.

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Using these readings in GemID: GemID's input panel accepts readings from all of these instruments directly. Enter your measurements and the app filters the candidate list in real time — the orange dot marks the next most useful test to run.