Lab-Grown Diamonds vs. Diamond Simulants vs. Mined Diamonds: What's the Difference?
Lab-grown diamonds are pure crystallized carbon, grown in a controlled laboratory environment. They share the same chemical, physical, and optical properties as an earth-mined diamond and are graded on the same scale. The only difference is where the diamond came from. You may see lab-grown diamonds referred to as lab-created diamonds, man-made diamonds, cultured diamonds, or grown diamonds. You may have also heard the term "synthetic diamond" — this is a misleading label set forth by the earth-mined diamond industry to imply that grown diamonds are somehow fake. They aren't. A lab-grown diamond is a real diamond.
Diamond simulants, on the other hand, are created to mimic the look of a diamond but contain zero diamond carbon and are non-precious. Cubic zirconia (CZ) and moissanite are the two most common simulants on the market, and each is discussed in detail below.
Earth-mined diamonds form naturally over billions of years under intense heat and pressure within the earth's crust, then are extracted through mining.
| Properties | Lab-Grown Diamonds | Cubic Zirconia | Earth-Mined Diamonds | Moissanite |
|---|---|---|---|---|
| % of Diamond Carbon Bonds | 100% solid | 0% | 100% solid | 0% |
| MOHS Hardness Scale | 10 | 8.0-8.5 | 10 | 9.25 |
| Cut | Varies by stone | Varies by stone | Varies by stone | Cut to correct its doubly refractive index |
| Color | D (colorless) to Z (light yellow) | Typically D, but can show yellow or green tinges under UV light | D (colorless) to Z (light yellow) | Typically I to J, with tinges of yellow, gray or green |
| Clarity | VS to SI | Usually flawless — manufactured, no natural inclusions | Variable — nearly always includes a natural birthmark | VS1 to VS2 |
| Carat Cost | Meaningfully less than an equivalent mined diamond | Avg $20.00 | Highest cost per carat | Avg $350.00 |
Note: diamond and gemstone pricing shifts often. The figures above are directional; check current pricing on our collection page for exact carat pricing.
Lab-Grown Diamond vs. Cubic Zirconia
Cubic zirconia (CZ) has been one of the most common diamond alternatives for decades – a manufactured zirconium oxide crystal designed to mimic a diamond's sparkle at a much lower price. Unlike a lab-grown diamond, CZ contains no diamond carbon at all. It's also noticeably softer, which means it's more prone to scratching/abrading, and its higher refractive index gives it a glassier, less fiery sparkle next to a genuine diamond. Over time, a CZ stone is more likely to cloud, scratch, or need replacing, something a lab-grown diamond, backed by the same hardness and durability as an earth-mined diamond, won't run into.
| Properties | Lab-Grown Diamonds | Cubic Zirconia | Summary |
|---|---|---|---|
| % of Diamond Carbon Bonds | 100% | 0% | Lab-grown diamonds are pure crystallized carbon. CZ is a manufactured zirconium oxide crystal with no diamond content at all. |
| MOHS Hardness Scale | 10 | 8.0-8.5 | CZ is noticeably softer, making it more prone to scratching and surface wear with everyday use. |
| Refractive Index | 2.42 | ~2.15-2.18 | CZ's lower refractive index gives it a flatter, glassier look next to a lab-grown diamond's brilliance and fire. |
| Color | D to Z, graded on the same scale as mined diamonds | Typically D, but can show yellow or green tinges under UV light | A lab-grown diamond holds its color permanently; CZ can develop a cloudy or tinted look over time. |
| Clarity | VS to SI | Usually flawless — manufactured, no natural inclusions | Both are typically eye-clean, though only the lab-grown diamond is graded on the diamond clarity scale. |
| Durability | Resists scratching and clouding indefinitely with proper care | Prone to surface scratches and clouding with regular wear | CZ is a popular entry-level stone, but it isn't built for the same everyday, long-term wear as a diamond. |
| Cost | Costs more per carat, but is a genuine diamond built to last | Lowest cost of any stone on this page, roughly $20 per carat | CZ's low upfront price often means the stone needs replacing down the road. |
Lab-Grown Diamonds vs. Mined Diamonds
MiaDonna has worked exclusively with lab-grown diamonds since 2007, partnering with leading labs to advance lab-grown diamond technology. A lab-grown diamond and an earth-mined diamond are chemically, physically, and optically identical – both are pure crystallized carbon with the same face-centered cubic structure, refractive index, and hardness. The only real difference is origin: one is grown in a controlled lab environment over a matter of weeks, the other forms naturally over billions of years and is extracted through mining. Because lab-grown diamonds skip large-scale mining, they come with a smaller environmental footprint, a guaranteed conflict-free origin, and a meaningfully lower cost per carat for the same size and quality.
| Properties | Lab-Grown Diamonds | Earth-Mined Diamonds | Summary |
|---|---|---|---|
| Chemical Composition | (C) Pure Carbon | (C) Pure Carbon | Both are 100% pure crystallized carbon. |
| Crystal Structure | Face-Centered Cubic / Singly Refractive | Face-Centered Cubic / Singly Refractive | Identical internal structure gives both diamonds the same brilliance, fire, and scintillation. |
| Refractive Index | 2.42 | 2.42 | Light bends identically through both stones because of their shared chemical composition. |
| MOHS Hardness Scale | 10 | 10 | Both are the hardest natural material on earth, making them ideal for daily wear. |
| Grading & Certification | Graded on the same 4Cs scale as mined diamonds. IGI is currently the leading lab issuing full 4Cs reports for lab-grown diamonds. | Graded on the 4Cs scale by independent labs, including GIA and IGI. | Independent labs certify both stone types, so you always know exactly what you're buying. |
| Production | Created in a controlled laboratory environment | Extracted through open-pit and underground mining | Lab-grown diamonds avoid the large-scale land disturbance and waste associated with diamond mining. |
| Sourcing | Guaranteed conflict-free, fully traceable to the lab where it was grown | Historically linked to human rights and environmental concerns; full traceability remains difficult even under certification schemes like the Kimberley Process | A lab-grown diamond gives you a fully documented, guaranteed conflict-free point of origin. |
| Cost | Meaningfully less per carat for the same size and quality | Highest cost per carat, especially for larger, high-color, high-clarity stones | The price gap between lab-grown and mined diamonds has widened substantially in recent years. |
MiaDonna is a certified B Corporation and partners with One Tree Planted to offset our environmental footprint, so choosing a lab-grown diamond means choosing a stone that's identical to a mined diamond in every measurable way, without the sourcing impact.
Lab-Grown Diamonds vs. Moissanite
Moissanite is a lab-created silicon carbide gem that entered the jewelry market as a diamond alternative in the late 1990s. It's harder and more durable than cubic zirconia, but its crystal structure is fundamentally different from a diamond's — and that difference shows up the moment light hits it. Moissanite is doubly refractive, which means light splits as it passes through the stone, creating a flashier, more colorful sparkle that can look unnatural next to a diamond, especially at larger carat weights.
| Properties | Lab-Grown Diamonds | Moissanite | Summary |
|---|---|---|---|
| Chemical Composition | Pure Carbon | Silicon Carbide | Moissanite is a different mineral altogether and contains no diamond carbon. |
| Internal Crystal Structure | Face-Centered Cubic / Singly Refractive | Hexagonal / Doubly Refractive | A diamond's singly refractive structure produces clean, focused brilliance. Moissanite's doubly refractive structure can create a fuzzy or "disco ball" doubling effect, most noticeable in larger stones. |
| Refractive Index | 2.42 | ~2.65-2.69 | Moissanite's higher refractive index makes it noticeably more fiery and colorful than a diamond, which can read as less natural side by side. |
| Color | D to Z, graded on the same scale as mined diamonds | Typically I to J, with tinges of yellow, gray or green | A lab-grown diamond stays colorless to near-colorless at any size; moissanite's tint becomes more visible as carat weight increases. |
| MOHS Hardness Scale | 10 | 9.25 | Both are highly durable for everyday wear, though a lab-grown diamond remains the hardest gem available. |
| Clarity | VS to SI | VS1 to VS2 | Both are typically eye-clean, though a lab-grown diamond is graded on the universal diamond clarity scale. |
| Cost | Higher cost than moissanite, but a genuine diamond | Mid-range cost — typically less than a lab-grown diamond | Moissanite offers a middle-ground price point, but it isn't diamond, and its optical differences are visible up close. |
