How to Read a Gemstone Lab Certificate: Every Field Explained

Most buyers glance at a certificate, see an official-looking layout, and file it away. The certificate is where a seller's claims become checkable - but only if you know which lines matter.

The fields, in order

Report number and date

The identifier you use to verify the report with the issuing laboratory. Note the date: a report more than a few years old may predate treatments the lab can now detect.

Species and variety

This is the most important line on the page. Species is the mineral - corundum, beryl, quartz. Variety is the specific stone - sapphire, emerald, amethyst.

It is what tells you whether your "Pukhraj" is corundum (yellow sapphire) or quartz (citrine sold as a substitute). If this line does not match what you were told you were buying, nothing else on the page matters.

Weight

Always in carats on a laboratory report. Convert to ratti yourself - multiply by 1.0989 - and compare with what you ordered. See carat vs ratti.

Dimensions and shape

Length × width × depth in millimetres, with cut and shape. Useful for confirming that the stone you received is the stone that was certified - measure it.

Colour

Descriptive rather than graded on most Indian reports. Some laboratories add a grade or a comparison to a master set.

Comments and treatment

The line that determines value, and the one most often left vague. Learn this vocabulary:

• "No indications of heating" or "unheated" - the premium designation.
• "Indications of heating" or "heat treated" - standard, widely accepted, lower price.
• "Clarity enhanced" - something was introduced into fractures. Ask what.
• "Minor / moderate / significant residue" - the oiling grade for emerald. Significant is a large reduction in value.
• "Lead glass filled" - common in cheap ruby. Fragile, low value, unsuitable for astrological use.
• "Diffusion treated" - colour added at the surface only. Avoid.
• "Dyed" - common in coral, turquoise and low-grade quartz.
• "Synthetic" / "lab-grown" / "created" - not natural, regardless of being chemically identical.
• "Assembled" / "doublet" / "triplet" - more than one piece bonded together.

A report with a blank or missing treatment field is not a clean report. It means the question was not asked. Ask for one that answers it.

Origin

Geographic origin - Ceylon, Burma, Colombia - is offered by some laboratories and carries a significant price premium. It is a probabilistic determination based on inclusion and trace-element analysis, not a certainty, and it matters far more to collectors than to astrological use.

Verifying the report itself

Fake certificates are common, and easy to produce.

1. Check the report number on the laboratory's own website, typing the URL yourself rather than following a link the seller provided.
2. Confirm the laboratory exists and has a verifiable address and history.
3. Look for security features - hologram, QR code, watermark, microprint.
4. Match the stone to the certificate. Measure the dimensions and check the photograph.
5. Be sceptical of in-house certificates from the seller's own "laboratory". They are not independent verification.
6. Prefer recognised laboratories - GIA, IGI, GRS, Gübelin and SSEF internationally; GII, GJEPC-recognised labs and IGI India domestically.

Rudraksha certificates are different

For a bead, look for X-ray or CT imaging showing the internal compartments, a stated mukhi count, a stated origin (Nepal or Indonesia), and a measured diameter. The X-ray is the meaningful part - it is what distinguishes a natural bead from one with carved lines.

Red flags

• A certificate that describes the stone only in vague terms with no species line.
• A report number that cannot be verified online.
• A certificate for a different weight or dimension than the stone you hold.
• Grand language - "premium quality", "highly effective" - which no real laboratory uses. Labs report facts, not efficacy.
• A seller who resists a request for an independent report.

Certificates issued with our products can be checked on the certificate validation page. Browse certified gemstones.