How to Read a Gemstone Certificate

A gemstone certificate is a laboratory's considered opinion about a stone. It is not a valuation and not a guarantee of price — but read correctly, it tells you almost everything that matters.

The five lines that count

1. Species and variety — for example corundum, variety ruby. This confirms the stone is what it is claimed to be.
2. Weight and measurements — check them against the stone in front of you. A mismatch is a red flag.
3. Colour description — laboratories use standardised terms. "Pigeon's blood" or "royal blue" carry weight only when issued by a recognised lab.
4. Treatment — the most important line. No indications of heating commands a premium; indications of heating is normal for much sapphire and ruby; filled fissures or diffusion change the value category entirely.
5. Origin — an opinion based on inclusions and trace chemistry. Reputable labs say so plainly and will decline to state an origin when the evidence is unclear.

Questions to ask

• Is the laboratory independent and internationally recognised?
• Is the report recent? Treatments can be applied after a report is issued.
• Does the report number verify on the laboratory's own website?

How SOMSTONE handles it

Every stone we present is inspected in-house and documented. For significant purchases we arrange third-party laboratory reports before you commit, and we tell you plainly what the report says — including anything that might lower the price.