Lab-Grown Diamonds vs Cubic Zirconia: Which Should You Choose?
When shopping for diamond jewelry—especially engagement rings—you’ll quickly encounter two popular alternatives to mined diamonds: lab-grown diamonds and cubic zirconia. Both look similar to the untrained eye, both cost less than natural diamonds, and both are created by humans rather than mined from the earth.
But that’s where the similarities end.
Choosing between a lab-grown diamond and cubic zirconia isn’t just about budget. It’s about durability, long-term appearance, resale value, and what the piece means to you. Pick the wrong one, and you might end up with a stone that scratches, clouds, or loses its sparkle within a few years. Pick the right one, and you’ll have a beautiful piece that holds up to daily wear and keeps its brilliance for decades.
Here’s the key difference in one sentence:
Lab-grown diamonds are real diamonds—chemically, physically, and optically identical to natural diamonds—while cubic zirconia is a synthetic material (zirconium dioxide) that mimics a diamond’s appearance but differs significantly in hardness, durability, and long-term performance.
In this guide, we’ll walk through how each option is made, how they compare in durability and sparkle, what they cost, and who should choose which—so you can make a confident decision.
What Is a Lab-Grown Diamond?
A lab-grown diamond (also called a lab-created diamond or man-made diamond) is a real diamond that’s grown in a lab instead of mined from the earth.
How Lab-Grown Diamonds Are Made
Lab diamonds are created using one of two methods:
- High Pressure High Temperature (HPHT) — mimics the natural conditions deep in the earth where diamonds form
- Chemical Vapor Deposition (CVD) — uses a diamond seed and carbon-rich gases to grow the crystal layer by layer
Both methods produce diamonds with the same chemical makeup (pure carbon arranged in a crystal lattice), the same optical properties, and the same physical hardness as natural diamonds.
Key Characteristics
- Hardness: 10 on the Mohs scale (the hardest natural material)
- Chemical composition: Pure carbon
- Appearance: Identical to natural diamonds—same brilliance, fire, and clarity
- Durability: Extremely durable; resistant to scratching and chipping
- Certification: Can be graded and certified just like mined diamonds (cut, clarity, color, carat)
Lab-grown diamonds are real diamonds. They share the same properties as natural diamonds—they just formed in a lab rather than underground over millions of years.
Explore a complete range of lab grown diamond jewlery at our store.
What Is Cubic Zirconia?
Cubic zirconia (CZ) is a synthetic material made from zirconium dioxide. It was developed in the 1970s as an affordable diamond alternative and is widely used in fashion jewelry, costume pieces, and budget-friendly engagement rings.
How Cubic Zirconia Is Made
CZ is created by melting zirconium oxide powder at extremely high temperatures, then cooling it to form crystals. The process is fast and inexpensive, which is why cubic zirconia is so affordable.
Key Characteristics
- Hardness: 8–8.5 on the Mohs scale (softer than diamonds)
- Chemical composition: Zirconium dioxide (not carbon)
- Appearance: Colorless and very sparkly when new—sometimes even “flashier” than a diamond due to higher dispersion
- Durability: Less durable than diamonds; more prone to scratching, clouding, and surface wear over time
- Weight: Cubic zirconia is slightly denser than diamonds, so a CZ stone will weigh more than a diamond of the same carat size
While cubic zirconia looks like a diamond at first glance, it’s not a diamond. It’s a diamond substitute with different optical properties, chemical properties, and long-term performance.
Lab-Grown Diamonds vs Cubic Zirconia: Head-to-Head Comparison
Let’s compare these two options across the factors that matter most when choosing a stone for an engagement ring or other diamond jewelry.
1. Chemical Makeup and Structure
| Factor | Lab-Grown Diamond | Cubic Zirconia |
|---|---|---|
| Chemical composition | Pure carbon (same as natural diamonds) | Zirconium dioxide |
| Crystal structure | Cubic crystal lattice (identical to mined diamonds) | Cubic crystal structure (similar, but chemically different) |
| Considered a “real diamond”? | Yes, lab-grown diamonds are real diamonds | No, CZ is a diamond simulant |
What this means for you: Lab diamonds have the same chemical properties as natural or mined diamonds. Cubic zirconia is chemically different—it’s not a diamond, but a synthetic material designed to mimic diamond’s appearance.
Read our guide on lab grown diamonds vs natural diamonds to learn more about the differences and similarities.
2. Hardness and Durability
| Factor | Lab-Grown Diamond | Cubic Zirconia |
|---|---|---|
| Mohs hardness | 10 (hardest natural substance) | 8–8.5 (softer) |
| Scratch resistance | Extremely resistant; won’t scratch from daily wear | Prone to surface scratches over time |
| Long-term durability | Will look new for decades with minimal care | May cloud, dull, or show wear within a few years |
What this means for you: Diamonds offer superior durability. A lab-grown diamond will stay brilliant and scratch-free even with daily wear. Cubic zirconia, being softer, will accumulate micro-scratches, lose its polish, and may start to look cloudy or dull—especially in high-contact areas like engagement ring settings. If you plan to wear the piece every day for years, durability matters.
3. Sparkle, Brilliance, and Fire
| Factor | Lab-Grown Diamond | Cubic Zirconia |
|---|---|---|
| Brilliance (white light reflection) | High; classic diamond sparkle | High when new, but can dull over time |
| Fire (rainbow flashes) | Moderate | Higher dispersion rate; more colorful flashes (can look “too rainbow-y”) |
| Appearance over time | Stays brilliant indefinitely | May lose sparkle as surface scratches accumulate |
What this means for you: When new, cubic zirconia can look extremely sparkly—sometimes even flashier than a diamond due to its higher dispersion. But this can make CZ look slightly “off” to a trained eye, and the sparkle fades as the surface wears. Lab-grown diamonds maintain their optical properties forever. They look the same in 20 years as they do on day one.
4. Weight and Density
| Factor | Lab-Grown Diamond | Cubic Zirconia |
|---|---|---|
| Density | Lower (3.52 g/cm³) | Higher (5.6–6.0 g/cm³) |
| Feel in hand | Lighter for the same size | Heavier for the same size |
What this means for you: A 1-carat CZ stone will feel noticeably heavier than a 1-carat diamond. This is one way jewelers can quickly spot the difference between cubic zirconia and a lab-grown diamond or natural diamond.
5. Cost
| Factor | Lab-Grown Diamond | Cubic Zirconia |
|---|---|---|
| Price range (1-carat equivalent) | $800–$2,500+ (depending on cut, clarity, color) | $10–$50 |
| Why the price difference? | Lab diamonds are real diamonds; production is complex and energy-intensive | CZ is inexpensive to manufacture |
What this means for you: Cubic zirconia is far more affordable, making it a popular choice for fashion jewelry, placeholder rings, or costume pieces. Lab-grown diamonds cost more, but still far less than mined diamonds, and offer the same quality, durability, and resale potential as natural diamonds.
6. Resale Value
| Factor | Lab-Grown Diamond | Cubic Zirconia |
|---|---|---|
| Resale value | Moderate (lower than mined diamonds, but still holds some value) | Essentially none |
| Can it be certified? | Yes, graded by GIA, IGI, etc. | No formal grading (it’s not a gemstone) |
What this means for you: If resale value matters—say, for an heirloom engagement ring or investment piece—a lab-grown diamond is the better choice. Cubic zirconia has no resale market; it’s considered disposable.
7. Maintenance and Care
| Factor | Lab-Grown Diamond | Cubic Zirconia |
|---|---|---|
| Cleaning | Simple: soap, water, soft brush; ultrasonic cleaners safe | Same cleaning methods, but won’t restore original sparkle if scratched |
| Professional care | Minimal; may need prong checks like any ring | May need replacement after a few years of wear |
What this means for you: Lab diamonds are low-maintenance and last indefinitely. Cubic zirconia may need to be replaced once it starts showing visible wear—common in engagement rings worn daily.
Spotting the Difference: Can You Tell CZ Apart from a Lab Diamond?
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To the untrained eye, it’s very difficult to tell the difference between cubic zirconia and a lab-grown diamond—especially when both are new, cut and polished, and set in the same ring.
However, jewelers and trained professionals can spot the difference using:
- Weight test — CZ is denser and will weigh more for the same size
- Hardness test — Diamonds score 10 on the Mohs hardness scale; CZ scores 8–8.5
- Thermal conductivity — Diamonds disperse heat quickly; CZ does not
- Loupe inspection — CZ may show internal imperfections or “doubling” of facets under magnification
Over time, the difference becomes more obvious:
- Lab diamonds stay brilliant
- Cubic zirconia may cloud, scratch, or lose polish after months or years of daily wear
Lab-Grown Diamonds and Cubic Zirconia vs Natural Diamonds
It’s worth briefly comparing both options to mined diamonds:
| Factor | Mined Diamond | Lab-Grown Diamond | Cubic Zirconia |
|---|---|---|---|
| Chemical makeup | Pure carbon | Pure carbon | Zirconium dioxide |
| Hardness | 10 | 10 | 8–8.5 |
| Optical properties | Same as lab diamonds | Same as natural diamonds | Different (higher dispersion) |
| Origin | Mined from earth | Grown in a lab | Synthetic material |
| Price (1-carat) | $3,000–$15,000+ | $800–$2,500 | $10–$50 |
| Resale value | High | Moderate | None |
| Durability | Excellent | Excellent | Good initially, declines over time |
Key takeaway:
Lab-grown diamonds share the same properties as natural diamonds—they’re real diamonds, just created in a lab instead of underground. Cubic zirconia is not a diamond; it’s an affordable simulant with different chemical composition, lower hardness, and less long-term durability.
How to Choose Between Lab-Grown Diamonds and Cubic Zirconia
Choose a Lab-Grown Diamond if:
- You want a real diamond with the same hardness, brilliance, and durability as a mined diamond
- You’re buying an engagement ring or other piece you’ll wear daily for years
- Resale value or future upgrades matter to you
- You want a stone that will stay brilliant forever with minimal care
- You value certification (GIA, IGI grading for cut, clarity, color, carat)
- Your budget allows for $800–$2,500+ for a 1-carat stone
Best for: Engagement rings, anniversary gifts, heirloom jewelry, or any piece meant to last a lifetime.
Choose Cubic Zirconia if:
- You want an affordable diamond alternative for fashion jewelry or costume pieces
- You’re looking for a placeholder ring while saving for a diamond
- You don’t plan to wear the piece daily, or you’re okay replacing it in a few years
- Cost is the primary concern (under $50 for a 1-carat equivalent)
- You’re buying jewelry for occasional wear, travel, or situations where you don’t want to risk a valuable stone
- Resale value doesn’t matter
Best for: Fashion rings, travel jewelry, placeholder engagement rings, costume pieces, or budget-conscious buyers who prioritize initial appearance over long-term durability.
Common Misconceptions: Lab Diamonds vs CZ
Myth 1: “Lab-grown diamonds aren’t real diamonds.”
Reality: Lab-grown diamonds are real diamonds. They have the same chemical makeup, crystal structure, hardness, and optical properties as naturally occurring diamonds. The only difference is where they formed—in a lab instead of deep underground.
Myth 2: “Cubic zirconia is just as good as a diamond.”
Reality: Cubic zirconia looks similar to a diamond when new, but it’s chemically different, softer (8–8.5 vs 10 on the Mohs scale), and less durable. Over time, CZ will scratch, cloud, and lose its sparkle—unlike diamonds, which stay brilliant indefinitely.
Myth 3: “You can’t tell the difference between CZ and a lab diamond.”
Reality: To the untrained eye, they look very similar—especially when new. But jewelers can easily tell the difference using weight, hardness, and thermal tests. And over time, the difference becomes obvious as CZ shows wear.
Myth 4: “Lab-grown diamonds are the same as cubic zirconia.”
Reality: Not even close. Lab diamonds are real diamonds (pure carbon, 10 on Mohs scale). Cubic zirconia is a form of zirconium dioxide—a completely different material with different properties and performance.
Myth 5: “CZ is a good long-term investment.”
Reality: Cubic zirconia has no resale value and will degrade over time. If you want a piece with lasting value, choose a lab-grown or natural diamond instead.
What About Moissanite?
If you’re comparing lab-grown diamonds and cubic zirconia, you may also come across moissanite—another popular diamond alternative.
Here’s how moissanite fits in:
| Factor | Lab-Grown Diamond | Moissanite | Cubic Zirconia |
|---|---|---|---|
| Chemical composition | Pure carbon | Silicon carbide | Zirconium dioxide |
| Hardness | 10 | 9.25 | 8–8.5 |
| Durability | Excellent | Excellent | Good initially, declines |
| Sparkle | Moderate fire | Very high fire (more rainbow flashes) | High dispersion when new |
| Price (1-carat) | $800–$2,500+ | $300–$600 | $10–$50 |
Who should choose moissanite?
Moissanite is a great middle ground: more durable than cubic zirconia, more affordable than lab diamonds, and offers a unique “fiery” sparkle that some buyers love. It’s ideal for those who want durability on a budget and don’t mind a slightly different look than a traditional diamond.
Summary: Lab-Grown Diamonds vs Cubic Zirconia
| Factor | Lab-Grown Diamond | Cubic Zirconia |
|---|---|---|
| What it is | Real diamond (pure carbon) | Synthetic zirconium dioxide |
| Hardness | 10 (Mohs scale) | 8–8.5 (Mohs scale) |
| Durability | Excellent; lasts forever | Good initially, wears over time |
| Sparkle | Classic diamond brilliance | High sparkle when new, dulls with wear |
| Cost (1-carat) | $800–$2,500+ | $10–$50 |
| Resale value | Moderate | None |
| Best for | Engagement rings, heirloom jewelry, daily wear | Fashion jewelry, placeholders, budget pieces |
Final Verdict: Which Should You Choose?
Choose a lab-grown diamond if:
You want a real diamond with the same hardness, brilliance, and durability as a mined diamond—at a fraction of the cost. Lab diamonds are ideal for engagement rings, anniversary gifts, or any jewelry meant to last a lifetime.
Choose cubic zirconia if:
You need an affordable, sparkly stone for fashion jewelry, travel, or a temporary placeholder. CZ looks great when new, but it won’t hold up to daily wear the way a diamond will.
Choose moissanite if:
You want durability close to a diamond, a unique fiery sparkle, and a mid-range price point.
Ultimately, the choice depends on how you’ll use the piece, how long you want it to last, and what it means to you. If it’s an engagement ring or heirloom, invest in a lab-grown diamond. If it’s a fun accessory or short-term solution, cubic zirconia is a practical choice.
FAQs: Lab-Grown Diamonds vs Cubic Zirconia
1. Are lab-grown diamonds real diamonds?
Yes. Lab-grown diamonds are real diamonds—they have the same chemical composition (pure carbon), crystal structure, hardness (10 on the Mohs scale), and optical properties as natural diamonds. The only difference is they’re grown in a lab instead of mined from the earth.
2. Will cubic zirconia look cloudy over time?
Yes, cubic zirconia tends to accumulate surface scratches and may lose its polish over time, especially with daily wear. This can make CZ look cloudy or dull compared to when it was new. Lab-grown diamonds, being much harder, stay brilliant indefinitely.
3. Can a jeweler tell the difference between cubic zirconia and a lab-grown diamond?
Yes. Jewelers can easily tell the difference using weight (CZ is denser), hardness tests, thermal conductivity, or loupe inspection. To the untrained eye, they may look similar when new, but experts and testing equipment can spot the difference immediately.
4. Is cubic zirconia a good choice for an engagement ring?
Cubic zirconia can work as a temporary placeholder or budget-friendly option, but it’s not ideal for long-term daily wear. CZ is softer than diamonds, scratches more easily, and may need to be replaced within a few years. For a lasting engagement ring, a lab-grown diamond offers better durability and resale value.
5. How much does a 1-carat lab-grown diamond cost compared to cubic zirconia?
A 1-carat lab-grown diamond typically costs $800–$2,500+ depending on cut, clarity, and color. A 1-carat cubic zirconia costs $10–$50. The price difference reflects the fact that lab diamonds are real diamonds with superior durability, while CZ is an inexpensive synthetic material.
6. Can you clean cubic zirconia the same way as a diamond?
Yes, you can clean both with warm soapy water and a soft brush. However, cleaning won’t restore cubic zirconia’s original sparkle if it has surface scratches. Lab-grown diamonds, being much harder, maintain their brilliance even after years of cleaning and wear.
7. Do lab-grown diamonds and cubic zirconia come in different shapes?
Yes, both lab-grown diamonds and cubic zirconia are available in all standard diamond shapes—round, princess, cushion, emerald, oval, pear, and more. Lab diamonds are cut and polished using the same techniques as mined diamonds, while CZ can be molded or cut into shape during production.