moissanites in infinity setting - diamond simulantsmoissanites in infinity setting - diamond simulants

Properties of Diamond Simulants

Diamond simulants, like cubic zirconia and moissanite, often appear in jewelry. See how the properties of real diamonds compare with popular imitations.

2 Minute Read

HomeLearning CenterGemologyReference Charts & MaterialsProperties of Diamond Simulants

IGS may receive customer referral fees from the companies listed in this page.

By International Gem Society
Diamond simulants often appear in jewelry, as side stones and accents as well as centerpieces. Identifying these lookalike materials, whether glass, cubic zirconia, or natural gems that resemble diamonds, is an important skill for gemologists. The chart below compares the physical and optical properties of natural diamonds with those of frequently encountered diamond simulants.
moissanites in infinity setting - diamond simulants
Two pear-cut moissanites in an infinity setting. © CustomMade. Used with permission.

This information, in conjunction with our article on distinguishing diamonds,  can help you separate diamonds from their imitators.

Identifying Synthetic Diamonds

Until relatively recently, gem-grade synthetic diamonds rarely appeared in jewelry. This is changing. Consult our article on identifying synthetic diamonds for advice on distinguishing natural or mined diamonds from their lab-created counterparts.

Interested in this topic?

This article is also a part of our Diamond Specialist Certification Course, in the unit Distinguishing Diamonds from Simulants and Synthetics.

View the Course

Properties of Natural Diamonds vs. Diamond Simulants

PropertiesNatural Diamond Type IaNatural Diamond Type IbNatural Diamond Type IIaNatural Diamond Type IIbMoissaniteCubic Zirconia
RI2.4172.4172.4172.4172.648 - 2.6912.15 - 2.18
BirefringenceNoneNoneNoneNone.043None
Dispersion.044.044.044.044.009 - .104.058 - .066
Optic CharacterIsotropicIsotropicIsotropicIsotropicUniaxial +Isotropic
PleochroismNoneNoneNoneNoneNoneNone
Read ThroughNoneNoneNoneNoneNoneSlight
LusterAdamantineAdamantineAdamantineAdamantineAdamantineSubadamantine
SG3.5153.5153.5153.5153.17 - 3.225.56 - 6.00
Hardness101010109 ¼8 - 8 ½
CleavagePerfect, four directionsPerfect, four directionsPerfect, four directionsPerfect, four directionsNoneNone
Absorption SpectraDark line at 415 and 478 nm, often moreIncreasing absorption towards blue endVariable, usually 504VariableNo sharp bands, strong absorption below 425Not diagnostic
UVColorless stones, inert to strong, usually blue (LW) Weaker (SW)Variable, can be inert, usually blue or yellowVariable, can be inert, often redInert but phosphoresce after exposure to SW UVBrownish yellow, (LW)Greenish/yellow or orangish/yellow (LW) Yellow (SW) Colored CZ varies
Girdle SurfaceWaxy, polished or granularWaxy, polished or granularWaxy, polished or granularWaxy, polished or granularFrosted, polished or striatedFrosted or polished
Facet JunctionsSharpSharpSharpSharpSharp or slightly roundedSharp or slightly rounded
Electrical TestNoneNoneVery WeakStrongFrequent, variable intensityNone
Thermal Test"Diamond""Diamond""Diamond""Diamond""Diamond""Simulant"
InclusionsBearding, crystals, planar grainingBearding, crystals, planar grainingBearding, crystals, planar grainingBearding, crystals, planar grainingBearding, crystals, planar grainingGas bubbles, negative crystals, unmelted powder
PropertiesGGGYAGSynthetic Spinel*White SapphireWhite TopazGlass
RI1.970 - 2.031.823 - 1.8431.720 - 1.7401.757 - 1.7791.609 - 1.6371.40 - 1.70
BirefringenceNoneNoneNone.008 - .010.008 - .010None
Dispersion.038 - .045.028.020.018.014.009 - .098
Optic CharacterIsotropicIsotropicIsotropicUniaxial -Biaxial +Amorphous
PleochroismNoneNoneNoneNone if totally colorlessNone if totally colorlessNone
Read ThroughModerateStrongStrongStrongStrongStrong
LusterVitreous to subadamantineVitreous to subadamantineVitreous to subadamantineVitreous to subadamantineVitreousVitreous
SG7.01 - 7.154.50 - 4.603.52 - 3.673.90 - 4.103.49 - 3.572.30 - 4.50
Hardness6.5 - 78.25 - 8.57.5 - 8985 - 6
CleavageNoneNoneNoneNonePerfect, 1 directionNone
Absorption SpectraNot diagnosticNot diagnosticNot diagnosticNot diagnosticNot diagnosticNot diagnostic
UVModerate to strong, pinkish orange (SW)Inert to moderate orange, (LW) Inert to weak orange, (SW)Occasionally, weak green (LW) Moderate to strong chalky or greenish blue, (SW)Natural: Inert to moderate red to orange (LW & SW)Synthetic: inert to weak, blueish white (SW)Not diagnosticNot diagnostic
Girdle SurfaceFrosted or polishedFrosted or polishedFrosted or polishedFrosted or polishedFrosted or polishedFrosted or polished
Facet JunctionsSlightly roundedSharp or slightly roundedSharp or slightly roundedSharp or slightly roundedSharp or slightly roundedRounded
Electrical TestNoneNoneNoneNoneNoneNone
Thermal Test"Simulant""Simulant""Simulant""Simulant""Simulant""Simulant"
InclusionsGas bubblesGas bubbles, curved striaeGas bubblesNatural: Silk, crystals, fingerprint, hexagonal banding. Synthetic: bubbles, curved striae, flux2 & 3 phaseBubbles, swirl lines, concave facets

Compliments of the International Gem Society.

Notes

* Colorless natural spinels are extremely rare. Should you encounter a colorless spinel as a diamond simulant, it's very likely synthetic.

For information on diamond color treatments, see our article on HPHT diamonds.

diamond simulants - moissanite ring
Moissanite engagement/wedding ring. Photo by 3BL Media. Licensed under CC By 2.0.

International Gem Society

View All Articles

Related Articles

More Articles
Diamond Value, Price, and Jewelry InformationJoel E. Arem</a>, PhD, FGA. Used with permission." src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" decoding="async" data-nimg="responsive" style="position:absolute;top:0;left:0;bottom:0;right:0;box-sizing:border-box;padding:0;border:none;margin:auto;display:block;width:0;height:0;min-width:100%;max-width:100%;min-height:100%;max-height:100%;object-fit:cover;object-position:50% 50%"/>

Diamond Value, Price, and Jewelry Information

Diamond is the most romanticized and heavily marketed of all gemstones. Nearly every jewelry establishment handles diamonds, even if it...
Read More
What Customers Value Most in the Jewelry Insurance Buying Experience

What Customers Value Most in the Jewelry Insurance Buying Experience

There are a lot of considerations when buying jewelry insurance. Here's how to find the best policy provider.
Read More
An Interview with “Diamond Wizard” Maarten de Witte: Part 4

An Interview with “Diamond Wizard” Maarten de Witte: Part 4

The American Rose Brilliant Cut© is an innovative design by diamond cutter Maarten de Witte. Learn how he created it...
Read More
An Interview with “Diamond Wizard” Maarten de Witte: Part 2

An Interview with “Diamond Wizard” Maarten de Witte: Part 2

“Diamond Wizard” Maarten de Witte faced many obstacles getting into the diamond trade. In this interview, he explains how he...
Read More

Latest Articles

More Articles
Classic Engagement Ring StonesPastel purple sapphire</a>, 1.08 cts, 5.8 mm, round cut, Sri Lanka. © <a href=https://www.gemsociety.org/article/diamond-and-simulant-comparison-chart/"https://www.thegemtrader.com/">The Gem Trader</a>. Used with permission." src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" decoding="async" data-nimg="responsive" style="position:absolute;top:0;left:0;bottom:0;right:0;box-sizing:border-box;padding:0;border:none;margin:auto;display:block;width:0;height:0;min-width:100%;max-width:100%;min-height:100%;max-height:100%;object-fit:cover;object-position:50% 50%"/>

Classic Engagement Ring Stones

Emerald, ruby, sapphire, and diamond are the most popular choices for classic engagement ring stones. Learn more about these traditional...
Read More
Broken Bangle — The Blunder-Besmirched History of Jade Nomenclature: Book Review

Broken Bangle — The Blunder-Besmirched History of Jade Nomenclature: Book Review

Is fei cui a better term for "pyroxene jade" than jadeite? Jeffery Bergman reviews Broken Bangle, a new book on...
Read More
Cuprite Value, Price, and Jewelry InformationJoel E. Arem</a>, PhD, FGA. Used with permission." src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" decoding="async" data-nimg="responsive" style="position:absolute;top:0;left:0;bottom:0;right:0;box-sizing:border-box;padding:0;border:none;margin:auto;display:block;width:0;height:0;min-width:100%;max-width:100%;min-height:100%;max-height:100%;object-fit:cover;object-position:50% 50%"/>

Cuprite Value, Price, and Jewelry Information

One of the rarest of all facetable gems, cut cuprites can show magnificent deep red color. However, these beautiful stones...
Read More
Gemstone Radiation TreatmentPhoto courtesy of <a href=https://www.gemsociety.org/article/diamond-and-simulant-comparison-chart/"https://www.liveauctioneers.com/">liveauctioneers.com and <a href=https://www.gemsociety.org/article/diamond-and-simulant-comparison-chart/"https://www.liveauctioneers.com/auctioneer/1081/eros-auctions-inc/">Eros Auctions, Inc</a>." src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" decoding="async" data-nimg="responsive" style="position:absolute;top:0;left:0;bottom:0;right:0;box-sizing:border-box;padding:0;border:none;margin:auto;display:block;width:0;height:0;min-width:100%;max-width:100%;min-height:100%;max-height:100%;object-fit:cover;object-position:50% 50%"/>

Gemstone Radiation Treatment

Gemstone radiation is a common but little understood technique for altering colors. Learn how it works and what gems usually...
Read More

Latest Community Discussions

Tanzanian Corundum

Tanzanian Corundum

Read More
Is This a Topazolite Garnet?

Is This a Topazolite Garnet?

Read More
Nigerian Gemstones

Nigerian Gemstones

Read More
Is This an Opal?

Is This an Opal?

Read More

Never Stop Learning

When you join the IGS community, you get trusted diamond & gemstone information when you need it.

Become a Member

Get Gemology Insights

Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!