How to Read a Gem Certificate

What a Gem Report Is — and Is Not

A gemmological laboratory report is an independent, expert description of a stone's identity and characteristics. It is not an appraisal of monetary value, and a reputable lab will never state a price. Instead, it documents the objective, verifiable facts about a gem so that buyer and seller share the same understanding of exactly what is changing hands.

The Trusted Laboratories

Not all reports are equal. The most respected coloured-stone laboratories include GRS (GemResearch Swisslab), SSEF, Gübelin, AGL (American Gemological Laboratories), and GIA. For coloured gemstones, GRS, SSEF and Gübelin are particularly respected for origin determination and treatment analysis.

Reading the Key Fields

• Identification / Species & Variety: The scientific name, e.g. "Natural Corundum, Variety: Blue Sapphire." "Natural" confirms the stone is not synthetic.
• Weight: Expressed in carats to two decimal places (1 carat = 0.20 grams).
• Dimensions: Length × width × depth in millimetres — useful for confirming the stone matches what you received.
• Shape and Cut: For example "Cushion, mixed cut" or "Oval, brilliant/step cut."
• Colour: The lab's standardised colour grade, sometimes with prized trade terms such as "Royal Blue" or, for ruby, "Pigeon's Blood" (used by GRS for top-saturation stones).
• Origin: The geographic source, where determinable — e.g. "Sri Lanka (Ceylon)" or "Mozambique." Origin is given as the lab's opinion based on inclusion and spectroscopic analysis.
• Treatment / Comments: The single most important section for value. "No indication of thermal treatment" is the phrase collectors look for. Other comments may note heating, minor or moderate clarity enhancement, or fracture filling.

Spotting a Genuine Report

Modern certificates carry security features: holograms, QR codes, microprinting, and a unique report number you can verify directly on the laboratory's website. Always cross-check the report number against the issuing lab's online database, and confirm that the dimensions and weight on the report match the stone in your hand.

Certification at MineralsHub

Wherever a stone is accompanied by a laboratory report, we publish its issuing lab and report number, and the original certificate ships with your purchase. For stones offered without a major-lab report, we say so plainly. A certificate is your gem's passport — and we want yours to travel with complete, verifiable documentation.