Cubic-Zirconia Vs Lab Diamond - Which is Best?

When choosing a diamond alternative, two popular options often come to mind: cubic zirconia and lab-grown diamonds. While both offer a sparkling, beautiful appearance, they differ significantly in terms of composition, durability, brilliance, and value. Understanding these differences is essential to making an informed decision that aligns with your budget, preferences, and long-term goals.

In this blog post, we’ll compare cubic zirconia and lab-grown diamonds across key factors like hardness, visual appeal, cost, and longevity. Let’s explore!

What is Cubic Zirconia?

Cubic zirconia (CZ) is a synthetic gemstone widely recognized for its brilliant sparkle and affordability, often used as a diamond substitute in jewelry.

First developed in the 1970s, CZ is made from zirconium dioxide through a controlled heating process that produces flawless, optically transparent crystals. Unlike natural or lab-grown diamonds, cubic zirconia is non-carbon-based, making it softer and more prone to scratches over time. 

Despite this, its versatility, wide range of colors, and budget-friendly nature have made it a staple in fashion jewelry, offering a glamorous look without the premium cost of diamonds.

For a deeper dive into diamond alternatives that offer similar brilliance and fire, check out our in-depth guide on lab-grown diamonds.

Cubic Zirconia vs Lab-Grown Diamond - In a Glance

Features	Lab-Grown Diamonds	Cubic Zirconia
Chemical Composition	Pure carbon (C)	Zirconium dioxide (ZrO2)
Hardness	10 (on the Mohs scale)	8.25 (on the Mohs scale)
Dispersion	0.044	0.066
Refractive Index	2.42	2.2
Purity	100% pure carbon, minimal inclusions	Contains impurities and no carbon
Clarity	Can achieve flawless clarity (VVS, IF)	Typically flawless or may have visible inclusions
Environmental Impact	Low sustainability with no mining	Low, no mining, but less sustainable in the production process

5 Key Differences Between Lab-Diamonds and Cubic Zirconia

While both are stunning alternatives to mined diamonds, their composition, durability, and brilliance set them apart in unique ways.

1. Chemical Composition

The primary distinction between lab-grown diamonds and cubic zirconia lies in their chemical composition, which directly impacts their appearance, durability, and value.

Lab-grown diamonds are composed of pure carbon, just like natural diamonds.

They are created in a controlled environment using advanced methods such as High-Pressure High-Temperature (HPHT) or Chemical Vapor Deposition (CVD). These processes replicate the natural conditions under which diamonds form, resulting in a crystal structure that is identical to that of mined diamonds.

This carbon lattice structure gives lab-grown diamonds their exceptional hardness, scoring a perfect 10 on the Mohs scale, and their unparalleled brilliance.

Cubic zirconia (CZ) is a synthetic material made from zirconium dioxide.

Unlike diamonds, it lacks carbon entirely. Its crystal structure is cubic, which contributes to its bright, flashy sparkle. However, CZ is significantly softer, with a Mohs hardness rating of 8-8.5, making it more prone to scratches and wear over time.

Its chemical makeup also causes it to have a higher dispersion of light, often resulting in a "rainbow-like" sparkle that can appear less refined compared to the fire of a diamond.

2. Appearance

Lab-grown diamonds possess the same optical properties as natural diamonds due to their identical carbon lattice structure. They exhibit the classic diamond brilliance, characterized by their ability to reflect white light (brilliance) and disperse colored light (fire).

Their refractive index, which measures how light bends through the stone, is approximately 2.42, the same as mined diamonds.

This creates the iconic sparkle that is synonymous with diamond jewelry. Additionally, lab-grown diamonds often have inclusions or slight imperfections, mirroring the unique appearance of natural diamonds, although they are typically fewer due to controlled growing conditions.

In the case of cubic zirconia (CZ), it has a higher dispersion rate of around 0.058–0.066 compared to a diamond’s 0.044, giving it a "rainbow-like" sparkle. This exaggerated dispersion can make CZ appear less sophisticated and overly flashy in natural light.

Its refractive index is lower, at approximately 2.15–2.18, contributing to a slightly less sharp brilliance. 

Furthermore, CZ is optically flawless because it is manufactured without natural inclusions, which some buyers perceive as a drawback due to its "too perfect" look.

Remember: Over time, appearance plays a role in durability. Cubic zirconia tends to dull and lose its sparkle due to its softness, which allows scratches and surface damage to accumulate. On the other hand, lab-grown diamonds are particularly notable as a direct, eco-friendly substitute that removes the ecological damage associated with conventional diamond mining.

Curious to see the hottest trends? Explore our curation of the best-selling lab-grown diamond jewelry to find your perfect match.

3. Environmental Impact

Diamonds created in laboratories offer an eco-friendly option compared to mined diamonds.

The creation of lab-grown diamonds does not include harmful mining methods that destroy forests, lead to soil erosion, and contaminate water sources. Because lab-grown diamonds are produced in a controlled laboratory environment, they have a significantly reduced carbon footprint.

While less significant than diamond mining, Cubic zirconia still needs energy during its production.

So, who wins the Sustainability award? Both win against the natural diamonds. ✨💎

Still, lab-grown diamonds are particularly notable as a direct, eco-friendly substitute that removes the ecological damage associated with conventional diamond mining.

4. Color

Do you know? The color in lab-grown diamonds depends on trace elements and the growth process.

Lab diamonds are available in both colorless and fancy-colored varieties, just like mined diamonds. The Gemological Institute of America (GIA) grades them on the same color scale, ranging from D (colorless) to Z (light yellow or brown).

For example, nitrogen may cause a yellow tint, while boron creates a blue hue. Advances in the HPHT and CVD techniques allow manufacturers to produce nearly flawless, colorless diamonds or intentionally create vivid, fancy colors for unique designs.  

Cubic zirconia (CZ) is inherently colorless and flawless, often appearing "too perfect." 

While this may initially be attractive, the lack of subtle color variations can make CZ appear artificial when compared to a diamond. Manufacturers can infuse cubic zirconia with pigments to mimic fancy-colored gemstones, but the color tends to be overly saturated and lacks the natural depth seen in diamonds.  

Note: Over time, aging and wear can also impact color. Lab-grown diamonds retain their color indefinitely due to their carbon-based composition and superior durability. Cubic zirconia, however, may develop a cloudy or yellowish tint with prolonged use, especially when exposed to oils, dirt, or cleaning chemicals. 

5. Price

Lab-grown diamonds are substantially less expensive than natural diamonds, typically costing 30-50% less for stones of comparable size, cut, and quality. This price reduction is due to their controlled production process, which eliminates the costs associated with mining and reduces supply chain complexities.

However, lab-grown diamonds still hold significant value because they are real diamonds with identical physical, chemical, and optical properties to their mined counterparts. Their pricing is influenced by the standard 4Cs: carat weight, cut, color, and clarity. Larger, higher-quality lab diamonds command higher prices, making them a premium yet accessible option.

In contrast, cubic zirconia (CZ) is an extremely budget-friendly alternative, with prices often 90-95% lower than both natural and lab-grown diamonds. A 1-carat CZ stone can cost as little as $10–$30, compared to thousands of dollars for a diamond of the same size.

This affordability stems from its inexpensive raw materials (zirconium dioxide) and mass production. However, cubic zirconia’s low price reflects its lower durability and lack of intrinsic value.

Important: Unlike lab-grown diamonds, CZ is not considered an investment, as it depreciates quickly and lacks long-term appeal due to wear and tear. So, when considering long-term value, lab-grown diamonds offer superior durability and resale potential, whereas cubic zirconia is best suited for temporary or budget-conscious purposes. 

Which is Better, Cubic Zirconia or Lab Diamond?

The choice between these two stones is not about which is "better" universally—it’s about aligning the gemstone with your specific priorities.

If you value authenticity, durability, and long-term brilliance, lab-grown diamonds are the clear winner, and we have given enough reasons for it already.

But if you are budget-prone, cubic zirconia excels as an affordable, short-term option for those seeking beauty on a budget. Its flawless appearance and accessibility make it a practical choice for fashion jewelry, one-off events, or as a temporary placeholder while saving for a diamond.

However, it lacks the durability and symbolic value of lab-grown diamonds, with a propensity to cloud and scratch over time.

So, choose what you can and need the most.