Moissanite vs Lab Grown Diamond: The Honest Comparison

A Lab Grown Diamond, also called a lab-created, man-made, cultured, or synthetic diamond, is a real diamond. It is crystallized carbon with the same crystal structure as a mined diamond, the same hardness, and the same way of bending light. It is graded by the same independent labs: IGI and GCAL issue full 4C reports for Lab Grown Diamonds, and as of October 1, 2025, GIA grades them on Premium and Standard descriptive tiers rather than the full 4Cs (Source: GIA, 2025-10-01). A jeweler cannot tell it from a mined diamond by eye. If you want the full picture on that, see our guide on Lab Grown vs mined diamonds and what a Lab Grown Diamond is.

Moissanite is a different material: silicon carbide. It was first identified in 1893 by the chemist Henri Moissan, who found tiny crystals of it in a meteorite crater in Arizona, and the gem is named after him. Natural moissanite is so rare that, in practice, all the moissanite sold today is lab-created. It is bright, hard, and inexpensive, which is why it became a popular diamond alternative. It is a real gemstone in its own right. It is simply not a diamond.

No. Moissanite is not a Lab Grown Diamond, and it is not a diamond of any kind. The confusion has an understandable source: nearly all moissanite sold today is created in a lab, so "lab-created" gets read as "lab grown diamond." But lab-created describes how a stone was made, not what it is. Moissanite is silicon carbide (SiC). A diamond, mined or Lab Grown, is crystallized carbon (C). Different element, different crystal, different stone.

The paper trail makes the same point. A Lab Grown Diamond is graded by the same independent labs that grade mined diamonds. Moissanite is never graded on a diamond report, because it is not a diamond.

A simulated diamond, also called a diamond simulant, is any material that imitates the look of a diamond but is made of a different substance and is not a diamond. The two most common simulants are moissanite, which is silicon carbide, and cubic zirconia, which is zirconium dioxide. Both are lab-made, both are affordable, and neither is a diamond.

A Lab Grown Diamond is not a simulant. It is a diamond: the same carbon crystal, hardness, and optics as a mined diamond, graded by the same independent labs. So a moissanite versus Lab Grown Diamond comparison is not two versions of one stone. It is a simulant next to the real thing. We make the full case in are Lab Grown Diamonds real diamonds.

Hardness

Diamond is the hardest material used in jewelry, a 10 on the Mohs scale. Moissanite's hardness is commonly cited near 9.25. Both are hard enough for daily wear, but a diamond is the most scratch-resistant stone you can put on a hand.

Sparkle and fire

This is the most visible difference. Moissanite has much higher dispersion than diamond (about 0.104 versus a diamond's 0.044), so it throws more rainbow flashes of color. Some people love that extra fire; others find it too flashy, sometimes called a disco-ball look. A Lab Grown Diamond has the balanced, mostly white brilliance people picture when they picture a diamond.

Color

Moissanite is usually near-colorless, though larger stones can show a faint warmth in some lighting, and premium grades are marketed as colorless. A Lab Grown Diamond is graded for color on the same D to Z scale as a mined diamond, so you can pick exactly where on that scale you want to sit, from icy colorless through the warmer grades. If a specific, graded color matters to you, that report-backed range is a real difference.

Telling them apart

A trained jeweler can usually identify moissanite, because it is doubly refractive: it splits light into two rays, which shows as a faint doubling of the facet edges under magnification. A diamond is singly refractive. A Lab Grown Diamond is the opposite case: because it is a diamond, it cannot be told from a mined diamond by eye and is confirmed only with lab equipment, which is why labs add an "LG" inscription on the girdle.

One caveat before anyone reaches for a pen tester: a basic thermal tester can read both moissanite and a diamond as diamond. A tester result is a starting point, not an identification. Reliable identification is the independent grading report and, if needed, a gemologist. Our guide on how to read a diamond grading report covers what to check.

Certification

A Lab Grown Diamond comes with an independent grading report you can confirm on the lab's own site. IGI and GCAL grade Lab Grown Diamonds on the full 4Cs; as of October 1, 2025, GIA grades them on Premium and Standard descriptive tiers instead (Source: GIA, 2025-10-01). Moissanite is not graded on the diamond 4Cs; it usually comes with a manufacturer warranty instead. If an independently graded, verifiable stone matters to you, that is a real difference.

Price

Moissanite is typically the least expensive of the options. A Lab Grown Diamond costs well under a comparable mined diamond, so it sits in the middle: a real, certified diamond for far less than mined.

The gap exists for a plain reason: these are different materials with different supply. Moissanite is silicon carbide, produced at scale specifically as a diamond alternative, so it is priced as an alternative. A Lab Grown Diamond is actual diamond crystal, grown, cut, and graded as a diamond. You are not paying more for a nicer version of the same stone; you are paying for a different stone.

Neither stone is mined. Moissanite is made in a lab, and a Lab Grown Diamond is grown in one, so both have an origin you can trace to a documented facility. That is the honest, defensible version of the origin point, and it applies to either choice.

What does not hold up is a blanket environmental label on either one. Growing a diamond is energy-intensive, and much of that energy still comes from carbon-heavy grids, so sweeping environmental claims are not well supported (FTC Green Guides, 2012). The statement that stays true is narrower: made, not mined. If sourcing matters to you, ask any seller where a stone comes from and what its report says, and judge the specifics rather than the label.

The choice comes down to what you want the stone to be. Both come in a wide range of shapes and settings, so styling is rarely the deciding factor, and a diamond also carries the traditional meaning most people attach to an engagement stone, while moissanite is the newer, less conventional pick. Neither is a financial investment. A ring is a love piece, something you buy to keep and to mean something.

When you're ready to see a real stone set in a real ring, browse our Lab Grown Engagement Rings collection.

Choose moissanite if

Choose a Lab Grown Diamond if

Whichever you choose, buy from a seller who tells you plainly what the stone is, and for a diamond, read the grading report and confirm it on the lab's own site.

Where Stienhardt fits: Stienhardt.com sells Lab Grown Diamonds, controls the Dutch Marquise cut via a special factory relationship, and hand-sets and finishes the stones in NYC. The Dutch Marquise is an elongated hexagonal cut, and the name is a trade name, not a grading term: on an IGI report it may read "Hexagonal Modified Brilliant," so verify the report itself. If you land on a real diamond, you can see the shape in our Dutch Marquise collection or browse our Lab Grown Diamond Engagement Rings.