One of the most common questions from moissanite buyers is: how do I know what I actually have? Whether you've purchased a moissanite ring and want to verify its identity, received a piece of jewelry and want to understand what the stones are, or simply want to understand how testing works, this guide provides a complete, accurate explanation of how gemstone testing technology interacts with moissanite — and what every result means.
The Two Types of Gemstone Testers
1. Thermal Conductivity Testers (the classic "diamond tester")
Thermal conductivity testers — the original and most widely available type of gemstone tester — measure how quickly a stone conducts heat away from a heated probe tip. Different materials have different thermal conductivity values:
- Diamond: extremely high thermal conductivity — reads as "diamond" on thermal testers
- Moissanite: very high thermal conductivity (the highest of any gemstone after diamond) — reads as "diamond" on thermal-only testers
- Cubic zirconia (CZ): low thermal conductivity — reads as "not diamond"
- Glass: very low thermal conductivity — reads as "not diamond"
What this means for moissanite buyers: A thermal-only tester CANNOT distinguish moissanite from diamond — both read as "diamond." If someone uses a thermal-only tester to "test" your moissanite and it reads "diamond," this confirms only that your stone has diamond-level thermal conductivity (which moissanite does), not that it is a diamond. Read more: Does Moissanite Pass a Diamond Tester?
2. Electrical Conductivity Testers (moissanite-specific testers)
Electrical conductivity testers measure a stone's electrical resistance. This technology was developed specifically to distinguish moissanite from diamond after thermal testers proved unable to do so:
- Diamond: does not conduct electricity (electrical insulator) — reads as "diamond"
- Moissanite: slightly conducts electricity (semiconductor) — reads as "moissanite" on electrical testers
- CZ: does not conduct electricity — may read as "diamond" on electrical testers (a limitation)
What this means: An electrical tester can distinguish moissanite from diamond. A moissanite reading on an electrical tester confirms your stone is moissanite, not diamond.
3. Combined Moissanite/Diamond Testers
Modern combined testers measure both thermal and electrical conductivity simultaneously, producing a three-way result: diamond, moissanite, or simulant (CZ/glass). These are the most accurate and informative testers available for consumer use. Combined testers have become the standard recommendation for anyone who needs to reliably distinguish between diamond, moissanite, and simulants.
The Doubling Effect: A Visual At-Home Test
Beyond electronic testers, there is a simple visual test that can identify moissanite with high reliability — the doubling effect. Moissanite is a doubly refractive material (it splits light into two separate rays as it passes through the stone). Diamond is singly refractive. When viewed through a jeweler's loupe or microscope through the side of the stone, moissanite's facet edges appear doubled (you see two lines where there is one facet edge). Diamond shows single, sharp facet edges without doubling.
This test requires a loupe (10× magnification) and correct viewing angle — it is not visible to the naked eye at normal viewing distances. It is, however, a reliable and free test that any loupe owner can perform. Read more: Does Moissanite Pass a Diamond Tester?
GRA Certification: The Definitive Authentication
For definitive authentication of your moissanite, the GRA certificate that accompanies all Moissanite Shine stones is the authoritative document. The GRA certificate specifies stone type (moissanite), color grade, clarity grade, cut grade, and carat weight — providing complete, laboratory-verified identity documentation that no at-home tester can match in authority. Read more: Moissanite Certificate & Authentication Guide.
Summary: What Each Test Result Means
- Thermal tester reads "diamond": Stone has high thermal conductivity. Could be diamond OR moissanite. Not conclusive.
- Electrical tester reads "moissanite": Stone is moissanite. Conclusive.
- Electrical tester reads "diamond": Stone is diamond or CZ (electrical testers do not distinguish these). Not conclusive for moissanite.
- Combined tester reads "moissanite": Stone is moissanite. Most reliable consumer test result.
- Doubling effect visible under loupe: Strong indicator of moissanite (or other doubly refractive stones). Confirms moissanite when combined with thermal "diamond" reading.
- GRA certificate: Definitive laboratory authentication. The highest authority.
All Moissanite Shine stones are GRA-certified DEF/VVS1 Excellent cut moissanite. Browse our collection: ring collection. Questions about your stone? contact us.
🛡️ Lifetime Gemstone Warranty — Your stones are protected forever.
⬆️ Lifetime Upgrade Program — Upgrade your stones or metal anytime.
✏️ Request a Custom Design — Make it uniquely yours.
📐 Not sure of your size? View our Ring Size Guide & Jewelry Care Tips
Related guides:
Does Moissanite Pass a Diamond Tester?
Moissanite Certificate & Authentication Guide
Moissanite vs. Cubic Zirconia Guide
Moissanite vs. Diamond Guide
Moissanite Grading Guide