How to tell if a lab-grown diamond is real

Short definition

A lab-grown diamond is a real diamond that is created in a laboratory rather than formed over geological time. It is chemically identical to a mined diamond and has the same basic physical properties, including hardness of 10 on the Mohs scale.

Quick checks you can do at home

Look for a laser inscription on the stone's girdle using a loupe or magnifier; many lab-grown stones have an inscription that cites a report number. Inspect the setting and mounting: low-quality metal and glue settings are common with simulants like cubic zirconia or glass but not definitive for real diamonds. Do a fog test: breathe briefly on the stone; fog from your breath clears very quickly on a diamond because it disperses heat. Use a bright light to check sparkle: diamonds show sharp white light (brilliance) mixed with colored flashes (fire). These simple checks can indicate whether the stone is a real diamond or a simulant, but they cannot reliably prove origin (lab-grown vs mined).

Tools professionals use

Gemologists use a loupe or microscope to look for growth patterns and inclusions typical of lab processes: CVD stones can show curved growth lines and HPHT stones can show metallic flux inclusions. Thermal conductivity testers register both mined and lab-grown diamonds as diamond. Specialized testers that measure electrical properties can separate moissanite from diamond because moissanite often gives a different electrical response. A spectroscope or advanced imaging can reveal growth features that indicate laboratory growth.

What a certificate tells you

A report from an established gem lab states whether the diamond is natural or lab-grown and lists grading details. Reputable labs also record any laser inscription on the girdle and will note the testing methods used. If a seller provides a grading report, compare the inscription or report number with the stone itself when possible.

Tests that do NOT prove natural origin

Thermal conductivity alone cannot tell a lab-grown diamond from a mined diamond because both are genuine diamonds. Simple at-home tricks — like the fog test or checking for brilliance — cannot determine whether a diamond is lab-grown or mined. Only microscopic examination by a trained gemologist or a gem lab report can determine the origin of a diamond reliably.

If you still need confirmation

If the stone must be identified with certainty, send it to a qualified gemological laboratory for an origin determination and report. A local independent jeweler with a gemologist can also inspect the stone and advise whether a full lab report is warranted. If you want an identification report from a dedicated tool, try Jewelry Identifier.

Common questions

Is a lab-grown diamond real diamond?

Yes. A lab-grown diamond is a real diamond; it is chemically identical to a mined diamond and shares the same hardness and many physical properties.

Can a home diamond tester tell if a diamond is lab-grown?

No. Home thermal testers identify diamond material but cannot distinguish lab-grown from mined diamonds. Only specialized lab equipment and microscopic examination can determine origin reliably.

How can I tell a diamond from moissanite or cubic zirconia?

Use a professional tester that checks electrical properties to separate moissanite from diamond, and inspect under magnification for hardness-related wear and inclusion patterns to distinguish cubic zirconia. A trained jeweller or lab can provide a definitive identification.

Keep reading

• How to tell if a chrysoberyl is real
• How to tell if a citrine is real
• How to tell if a demantoid is real

Sources

• GIA — Gemological Institute of America
• 16 CFR Part 23 — FTC Guides for the Jewelry Industry