Lab-Grown Diamonds vs. Cubic Zirconia: Key Differences (2026)

Lab-grown diamonds and cubic zirconia can both offer a bright, colorless look at a lower price than mined diamonds. The essential difference is simple: a lab-grown diamond is a real diamond, while cubic zirconia is a diamond simulant made from a different material.

That difference affects durability, sparkle, weight, long-term appearance and price. This guide compares those points so you can decide whether you want fine diamond jewelry or an inexpensive look-alike. Moissanite is another, separate diamond alternative with different optical and physical properties.

The naming can be especially confusing at brands that sell more than one material. For a real-world example, our Swarovski Created Diamonds review separates the company's lab-grown diamonds from its better-known crystals.

Our comparison combines gemological references with Klaus and Juli's experience buying and examining diamond jewelry in stores and at home. We compare the materials at normal viewing distance as well as through specifications, because magnified product images alone can make both look more alike—or more different—than they do when worn.

What Is a Lab-Grown Diamond?

A lab-grown diamond, also called a lab-created diamond, is a real diamond grown by people rather than mined from the earth.

The two main growth methods are High Pressure High Temperature (HPHT) and Chemical Vapor Deposition (CVD). Both begin with a diamond seed and create rough diamond crystal under controlled conditions.

The result has the same carbon crystal structure and core optical and physical properties as a mined diamond. Lab-grown production avoids diamond mining and its local land, pollution, labor and conflict risks. Its environmental advantage is strongest when growers use efficient processes and low-carbon or renewable electricity.

A lab-grown diamond

What Is Cubic Zirconia?

Having learned that lab-grown diamonds are indeed real diamonds, what about cubic zirconia?

Cubic zirconia, also known as CZ, is a synthetic diamond simulant composed primarily of zirconium dioxide. This synthetically created stone mimics the look of real diamonds but lacks their hardness and durability.

Cubic zirconia is a synthetic gemstone, but it is not diamond. Its cubic crystal form can create a diamond-like appearance even though its chemistry and physical properties are different.

The History of Cubic Zirconia

Cubic zirconia has been used since the 1970s as an affordable diamond alternative. This synthetically created stone is made from zirconium dioxide and shares a cubic crystalline form with diamonds.

Cubic Zirconia Chemical Structure

Both materials have cubic crystal structures, but their chemistry is different. Lab-grown diamonds are crystalline carbon. Cubic zirconia is zirconium dioxide, usually stabilized with another oxide so the cubic structure remains at room temperature.

How Cubic Zirconia Is Made

Creating cubic zirconia involves melting powdered ingredients at high temperature and cooling the material into crystals. These crystals are then cut and polished in many of the same outlines used for diamonds.

The Appeal of Cubic Zirconia Over Real Diamonds

Cubic zirconia offers a diamond-like look for much less than either mined or lab-grown diamond. A well-cut CZ can look bright and attractive, making it useful for inexpensive fashion jewelry.

Another advantage is the ability to choose a large stone without a high price. Larger diamonds, including lab-grown ones, generally cost more when other qualities are similar. Compare millimeter measurements as well as carat weight: CZ is denser, so equal weights do not mean equal sizes.

Lab-Grown Diamonds vs. Cubic Zirconia: Pros and Cons

Lab-grown diamond is our choice for a real diamond worn often over many years. CZ suits a much lower budget, occasional wear or a temporary ring. The differences below explain what you get for the extra cost.

Differences Between Cubic Zirconia vs. Lab-Grown Diamonds

The stones can look similar at first glance, but their chemistry and physical properties differ.

Composition

In terms of composition, too, they vary greatly. While lab-grown diamonds consist almost entirely of pure carbon, just like their natural counterparts, cubic zirconia contains no carbon. Instead, cubic zirconia consists mainly of a stabilized version of the mineral baddeleyite, also known as ‘ZrO2’ or ‘zirconium dioxide’.

Durability and Hardness

On the Mohs hardness scale, for example, while a real diamond ranks at 10 – making it one of the hardest substances known to man – cubic zirconia scores an 8 to 8.5, meaning it’s less durable than its diamond counterparts.

CZ's lower resistance to scratching means surface wear can dull its sparkle over time. Lab-grown diamond resists scratches much better, but a hard knock can still chip it. Hardness measures scratch resistance, not protection against every kind of damage.

Mohs hardness scale

Clarity Grade

Cubic zirconia is commonly manufactured with few visible inclusions. Lab-grown diamonds can have growth features and inclusions, just as mined diamonds can. Clarity alone is not a reliable origin or material test.

Color Grade

Both materials are available in colorless and colored varieties. Lab-grown diamonds range from colorless and near-colorless stones to fancy colors such as blue and pink. CZ can also be made in many colors.

Color alone is also not a reliable test: both materials can be made or sold in colorless and colored varieties.

Eco-friendliness

Both materials avoid the direct land disturbance and many of the local pollution, labor and conflict risks associated with mining. Their total environmental footprint still depends on energy, raw materials, factory efficiency and transport. For lab-grown diamonds, renewable or low-carbon electricity can make the advantage over mining much stronger.

Can You Tell Cubic Zirconia From Lab-Grown Diamonds?

The world of lab-grown diamonds and cubic zirconia stones can be confusing for many and, at first, glance, may look similar. Both are popular choices in the jewelry market, but can you tell the difference between lab-grown diamonds vs. cubic zirconia?

Separating diamond from CZ is generally simpler for a jeweler than identifying a diamond's mined or laboratory-grown origin. Visual clues can help explain the differences, but they are not a dependable identification test.

1. Weight: Cubic zirconia is heavier than diamond, and 1-carat of cubic zirconia will be smaller than 1-carat lab-grown diamonds.
2. Brilliance: Diamonds show white sparkle and colored flashes. CZ usually shows more colorful fire and a different balance of reflected light.
3. Clarity: CZ commonly has few visible inclusions. Lab-grown diamonds range in clarity, including very high grades, so a clean-looking stone alone does not identify the material.
4. Color: Both can be colorless or colored. A colorless stone is not evidence that it is CZ.
5. Scratches and cloudiness: Surface wear can dull CZ. Dirt can make either material look cloudy, so clean the piece safely before judging its appearance.

These observations can suggest a difference but cannot identify a stone reliably. A jeweler or gemologist can use thermal, optical and other testing tools. For a significant diamond purchase, use a grading report rather than relying on a home visual test.

Cost Comparison: Lab-Grown Diamonds vs. Cubic Zirconia

CZ costs less at the outset. Lab-grown diamond costs more, but gives you a real diamond with much greater scratch resistance. Compare the whole piece, including its metal and setting, rather than the stone alone.

Lab-Grown Diamond Costs

Lab-grown diamonds can cost 60–80% less than comparable mined diamonds. They are not imitations: they offer diamond's sparkle and durability while avoiding mining. The environmental benefit depends particularly on the energy used for growth and manufacturing.

Our live lab-grown diamond price guides use 2026 seller research and authorized catalog data. A loose one-carat lab-grown diamond can now cost a few hundred dollars at the value end of the market, with large differences for cut, color, clarity, grading report and seller.

Cubic Zirconia Costs

Cubic zirconia is the budget-friendly option. Frequent wear may mean replacing a scratched stone sooner than you would a diamond, so consider the setting and replacement cost as well as the purchase price.

But cubic zirconia remains far less expensive. Small loose stones and simple jewelry can cost tens of dollars, while a graded one-carat lab-grown diamond typically costs hundreds. Compare complete jewelry prices rather than carat labels: cubic zirconia is denser than diamond, so equal carat weights do not have equal dimensions.

You can even pick up a pair of cubic zirconia earrings set with 1 carat CZ each for less than $40.

CZ can give a convincing diamond-like look for very little money. Diamond's advantage is its greater resistance to scratching and its different optical character, not that CZ can never look attractive.

Quality vs. Price

Cubic zirconia wins on initial price. A lab-grown diamond costs more but offers diamond's greater hardness and long-term resistance to scratching. Neither should be purchased primarily for resale value; choose according to the intended wear and budget.

Why Choose Lab-Grown Diamonds Over Cubic Zirconia?

Both cost less than mined diamond, but only lab-grown diamond is diamond. We favor it for fine jewelry intended for frequent, long-term wear.

Disadvantages of Cubic Zirconia

The main trade-offs are surface wear and the way the stone handles light. Whether those matter enough to spend more depends on how you will wear the jewelry.

Aesthetic appeal

Both can be cut into familiar shapes such as round, oval and emerald cut. We prefer diamond's balance of brightness and colored flashes, especially in an engagement ring. CZ can still be a good-looking choice for a much smaller budget.

Durability and Hardness

Diamond's hardness of 10 makes it more resistant to scratching than CZ at about 8–8.5. Over years of daily wear, that difference favors diamond. Both stones still need secure settings and protection from hard knocks.

Artificial Brilliance and Fire

Brilliance is the white light reflected from a stone; fire is the light split into colors. CZ generally shows more fire and less brilliance than diamond. We prefer diamond's balance, but cut, lighting and personal taste also affect how you judge the sparkle.

Thermal conductivity

Diamond conducts heat much more effectively than cubic zirconia, which is why thermal conductivity is useful in professional testing. Do not expose jewelry to heat or rely on improvised home tests; settings and other diamond simulants can complicate the result.

Bottomline

Lab-grown diamonds offer the same carbon composition and fundamental physical properties as mined diamonds while avoiding mining. Cubic zirconia is a separate synthetic gemstone designed to offer a diamond-like appearance at a much lower price.

If you want a real diamond for an engagement ring or jewelry intended for frequent, long-term wear, lab-grown diamond is usually the stronger choice. Cubic zirconia makes sense when the lowest possible price matters more than durability and lasting appearance.

For occasional jewelry or the lowest possible price, cubic zirconia can be perfectly suitable. For frequent wear and diamond's long-term hardness and optical character, we would choose a lab-grown diamond.

Where to buy lab-grown diamonds

If you choose a lab-grown diamond, compare the individual grading report, video, measurements and complete jewelry price. These jewelers are useful starting points for different priorities:

GIA classifies cubic zirconia as a diamond simulant: it can imitate the look, but it has a different composition, crystal structure and physical properties. GIA lists CZ at 8.5 on the Mohs hardness scale, compared with 10 for diamond. See GIA's guide to imitation gems and its laboratory-grown diamond Q&A.