Moissanite vs Diamond: Key Differences, Testers and Price

Lab-created moissanite is not a diamond. It is a distinct gemstone made of silicon carbide, while diamond is crystallized carbon. Moissanite ranks 9.25 on the Mohs hardness scale versus diamond's 10, can show more rainbow-colored fire, and often costs less than a comparably sized natural or lab-grown diamond. Here is how the two compare, how jewelers tell them apart, and what to check before you buy.

Moissanite vs diamond at a glance

The moissanite figures are published gemological reference values from GIA's 1997 study of jewelry moissanite, and GIA's December 2025 guide to diamond alternatives confirms the 9.25 Mohs hardness. The diamond figures (hardness 10, specific gravity about 3.52, refractive index 2.42) come from the FTC Jewelry Guides. At equal volume, moissanite's specific gravity of 3.22 makes it about 9% lighter than diamond. Brilliant Earth's guide (updated June 2026) lists a refractive index of 2.64 to 2.69 for moissanite and describes "more than twice the amount of fire." These figures describe the gem materials in general, not measurements or certifications of individual stones.

Looking for finished jewelry rather than a loose stone? Explore our lab-created moissanite jewelry, with necklaces, earrings and bracelets in sterling silver.

What is moissanite?

Moissanite is the mineral form of silicon carbide. It occurs in nature only in tiny amounts, so the moissanite set in jewelry is made in a laboratory. GIA's study describes its key traits: two refractive indices of 2.648 and 2.691, a dispersion of 0.104, a hardness of 9¼ on the Mohs scale and a specific gravity of 3.22. When marketing jewelry containing lab-created moissanite, sellers must clearly disclose its laboratory origin. Under the FTC Jewelry Guides, that disclosure should immediately precede the gemstone name and be equally conspicuous.

Is moissanite a diamond?

No. Under the U.S. Federal Trade Commission's Jewelry Guides (16 CFR Part 23), a diamond is "a mineral consisting essentially of pure carbon crystallized in the isometric system." Moissanite is silicon carbide, so it must never be sold as a diamond. The same Guides say a lab-made stone's name must be immediately preceded by a word such as "laboratory-created" or "laboratory-grown," and that words like "natural" or "genuine" may not describe a stone made artificially.

Is moissanite a fake diamond?

No. Lab-created moissanite is a distinct gemstone with its own chemical and optical properties. It can be used as a diamond simulant because it resembles diamond, but the gemstone material itself is silicon carbide, not diamond or glass.

Moissanite vs lab-grown diamond

A lab-grown diamond is a diamond produced in a laboratory. It consists of carbon with the same crystal structure and essentially the same optical and physical properties as a mined diamond. Moissanite is a different stone. The main differences:

• Look: a lab-grown diamond sparkles like a mined diamond. Moissanite can show more colorful fire, often easier to notice in larger stones.
• Hardness: 10 for any diamond, 9.25 for moissanite. Both suit everyday jewelry.
• Price: lab-grown diamonds usually cost less than natural diamonds of the same size but generally more than moissanite.
• Testing: both natural and lab-grown diamonds generally register as diamond on a thermal tester. Combined thermal and electrical testers can help distinguish moissanite, but some lab-grown and blue diamonds can produce misleading results.

Does moissanite pass a diamond tester?

On a basic tester, often yes. Traditional "diamond testers" measure how quickly a stone carries heat, and GIA found that thermal probes react to moissanite as if it were diamond. As Brilliant Earth's tester guide (updated August 2026) explains, a multi-tester that measures thermal and electrical conductivity can often help distinguish moissanite from diamond. However, GIA links boron to electrical conductivity in some diamonds and reports that colorless to near-colorless HPHT lab-grown diamonds usually contain detectable boron impurities, so some boron-containing diamonds may give misleading electrical-tester readings. Trace boron alone does not show how a particular stone will test. A trained jeweler may also look for doubled facet edges under magnification, because moissanite is doubly refractive, although that feature can be difficult to see from certain angles. Additional gemological testing may be needed when the result is uncertain.

Which sparkles more, moissanite or diamond?

Moissanite has a higher refractive index and more than twice the dispersion of diamond, so it can display more rainbow-colored flashes, depending on the stone's cut and lighting. Diamonds often show a different balance of white brilliance and colored fire. Neither is better; it comes down to whether you love a lively, colorful sparkle or a classic white one.

Is moissanite cheaper than a diamond?

Usually. Brilliant Earth's June 2026 guide describes moissanite as generally less expensive than diamond. Because the two stones have different densities, comparing stones of similar visible dimensions is more useful than comparing carat weight alone. For stones of similar visible dimensions, natural diamonds are often priced above lab-grown diamonds, while lab-created moissanite is often less expensive than either. Prices can overlap depending on the stone's specifications and setting. Exact prices vary with size, cut, color and setting, so check whether a listing gives actual carat weight or diamond-equivalent weight.

Is moissanite good for everyday jewelry?

Yes. At 9.25 on the Mohs scale, GIA describes moissanite as one of the hardest gemstones available, second only to diamond, which makes it well suited to necklaces, earrings and bracelets worn every day. Like any gemstone, it can still chip from a hard knock, and the durability of a finished piece also depends on its setting and metal.

Is moissanite colorless?

Moissanite sold for jewelry is available in colorless and near-colorless varieties. Some stones can show a faint yellow or gray tint in certain lighting, especially in larger sizes. Diamonds are graded for color on their own scale, and a diamond color grade does not transfer to moissanite.

What is the downside of moissanite?

• It is slightly softer than diamond, though 9.25 on the Mohs scale is still very hard for daily wear.
• Its rainbow fire can look different from diamond to a trained eye, especially in larger stones.
• Moissanite dimensions are often given in millimeters; some listings also use diamond-equivalent weight (DEW), because moissanite is less dense than diamond. Check how a listing measures its stones before comparing prices.

How we describe our moissanite

We want every listing to be easy to trust, so we follow a few plain rules:

• Every moissanite stone we sell is lab-created moissanite, and we never call it a diamond.
• Some designs combine lab-created moissanite with other accent stones, including cubic zirconia. A product title containing "moissanite" does not mean every stone in the design is moissanite. Check the individual listing for its confirmed gemstone details.
• Where a product page lists a clarity grade, that grade comes from supplier-provided specifications and has not been independently verified by us. We do not claim GIA grading or independent gemological certification for these pieces.
• Our moissanite collection includes platinum-plated 925 sterling silver and other 925 sterling silver finishes. Check each product page for its specific metal and finish.

For example, the Heart of Light Moissanite Necklace has a heart-shaped lab-created moissanite center in a pavé halo of small accent stones, and the Radiant Butterfly Moissanite Necklace features a round lab-created moissanite at its center, with baguette-cut accent stones in the wings. In the Faith & Light Layered Set, only the round solitaire is moissanite; the stones in the cross are cubic zirconia.

Frequently asked questions

Is moissanite better than a diamond?

Neither is better for everyone. Diamond is harder and typically shows a different balance of white brilliance and colored fire. Moissanite often costs less for a similar look and can show more colorful fire. Choose based on the sparkle you love and your budget.

Can a jeweler tell moissanite from a diamond?

Usually, yes. Jewelers can combine conductivity testing, magnification and other gemological methods. No single handheld tester is completely reliable for every diamond and moissanite.

How much does a 1-carat moissanite cost?

There is no single fixed retail price for a 1-carat moissanite. Pricing depends on the stone's dimensions, cut, color, quality and jewelry setting. Some listings use diamond-equivalent weight rather than actual moissanite carat weight, so check the dimensions in millimeters and what the listed carat figure represents before comparing prices.

Is moissanite real?

Moissanite is a true mineral species, silicon carbide, not a diamond and not glass. The moissanite used in jewelry is made in a laboratory, so it is correctly sold as lab-created moissanite.

How do I care for moissanite jewelry?

Wipe your jewelry gently with a soft, dry cloth after wear. Remove it before showering, swimming or exercising, and keep it away from perfume, lotions, chlorine and harsh cleaning products. Store each piece separately to help protect its metal finish and setting.

Shop lab-created moissanite jewelry

Explore our lab-created moissanite jewelry collection, including necklaces, earrings and bracelets in 925 sterling silver. Each product page lists its specific metal finish, gemstone details and dimensions.