Lab Grown Diamonds vs Cubic Zirconia: Why They Are Not the Same

Ladies, you have probably heard someone say it at least once. "Lab grown diamonds? Isn't that just like CZ?"

It is one of the most common comparisons in fine jewellery, and if you have ever found yourself explaining a solitaire ring or pendant, you may have encountered the same question.

The answer is no. Lab grown diamonds and cubic zirconia are not the same. Lab grown diamonds are real diamonds made of crystallised carbon, with the same chemical, physical, and optical properties as mined diamonds. Cubic zirconia is a diamond simulant made from zirconium dioxide, created to resemble a diamond's appearance but fundamentally different in composition.

The comparison exists because both are created above ground, both offer an alternative to mined diamonds, and both can appear bright and colourless at first glance. However, that visual similarity is where the overlap ends. They differ significantly in durability, brilliance, certification standards, and long term performance.

One is a diamond in the scientific and gemological sense of the word. The other is a simulant designed to mimic the look of a diamond. Understanding that distinction is essential when evaluating quality, longevity, and value in fine jewellery.

If you are looking for a clear and honest comparison between lab grown diamonds and cubic zirconia, this guide will walk you through the differences that matter most.

Lab Grown Diamonds vs Cubic Zirconia: Quick Comparison

Before we get into the finer details, the table above highlights the most important distinction: lab grown diamonds are real diamonds with the same fundamental properties as mined diamonds, while cubic zirconia is a separate material created to imitate a diamond's appearance.

The Raw Material Is Where Everything Diverges

The most important difference between a lab grown diamond and cubic zirconia is not visible to the eye. It is in what each one is actually made of.

Lab grown diamonds are made of 100% crystallized carbon, the same material as a mined diamond. The process of creating them in a laboratory, whether through High Pressure High Temperature (HPHT) or Chemical Vapor Deposition (CVD) technology, replicates the conditions under which diamonds form naturally. The result is a diamond that is chemically, physically, and optically identical to one pulled from the earth. Not similar to. Identical too.

Cubic zirconia is made of zirconium dioxide. It contains no carbon. It has no chemical relationship with a diamond. CZ was originally developed in the 1970s primarily for industrial and scientific purposes, and its role in jewellery came later because of its visual resemblance to diamonds at a very low cost of production.

This distinction shapes everything that follows, from durability to certification. A lab grown diamond is a diamond. Cubic zirconia is a synthetic simulant and belongs to the category of diamond simulants, materials created to visually resemble diamonds without sharing their composition.

The Sparkle Is Not Interchangeable

Both lab grown diamonds and CZ lab diamonds catch light. But the kind of light they throw is very different, and once you know what to look for, it becomes easy to spot.

Lab grown diamonds produce what gemologists call brilliance, which is the crisp, bright, white light reflected back from within the diamond. This comes from the specific way carbon crystallizes into a diamond lattice structure. It is a clean, deep sparkle that looks the same whether you are in candlelight or afternoon sun.

Cubic zirconia has a higher optical dispersion value than a diamond. In practical terms, this means CZ scatters light into more colourful, rainbow-like flashes rather than that signature white brightness. Jewellers sometimes call this the "disco ball effect." It is not a flaw in CZ; it is simply the nature of the material, but it is visually distinct from the way a lab grown diamond catches light.

If a piece ever looked almost too flashy, too prismatic in a way that felt slightly off to you, you were likely looking at a CZ.

What Happens After Real, Daily Life

This is where the practical difference between lab grown diamonds, often referred to as synthetic diamonds, and cubic zirconia becomes most relevant for someone who plans to actually wear their jewellery.

Lab grown diamonds score a 10 on the Mohs Hardness Scale. They are the hardest known mineral. A lab grown diamond worn through daily routines, meetings, workouts, weekends, and every ordinary Tuesday in between will look the same ten years from now as it does today. It does not scratch. It does not cloud. It holds its brilliance indefinitely.

Cubic zirconia scores between 8.25 and 8.5 on the Mohs scale. On the surface, that gap sounds small. But the Mohs scale is not linear. Each point represents an exponential difference in scratch resistance. CZ will scratch against harder everyday surfaces. It chips more easily. With regular wear, most CZ pieces begin to show visible cloudiness and surface dullness within two to three years.

This is not a deficiency in CZ as a material. It was never designed for the kind of committed, lifelong daily wear that fine diamond jewellery is built for. It is designed for fashion pieces, for trend-led looks, for occasions where you want sparkle without long-term investment. The issue arises only when someone purchases CZ believing it will behave like a diamond over time.

The Clouding That Nobody Warns You About

Most comparisons between lab grown diamonds and cubic zirconia mention hardness. Very few mention what happens to CZ's surface over time, and it is one of the most important things to understand before making a jewellery decision.

Cubic zirconia, often referred to as an artificial diamond in fashion jewellery conversations, has a slightly porous surface structure at a microscopic level. Over time, regular contact with skin oils, soap, lotion, and moisture leaves a film that gradually builds up. You can clean a CZ piece, and it will temporarily look brighter, but the cloudiness comes back. Eventually, it becomes a permanent dullness that no amount of cleaning fully reverses.

A lab grown diamond does not behave this way. Its crystallized carbon structure is entirely non-porous. A simple clean with warm water and mild soap restores a lab grown diamond to the same brilliance it had on day one, whether that day was last month or ten years ago.

For jewellery intended for everyday wear, this difference becomes especially important. 

A Word on Weight and Size

Here is a detail that surprises most people: cubic zirconia is actually denser than a diamond. If you were to hold a 1 carat CZ and a 1 carat lab grown diamond side by side, the CZ would feel noticeably heavier and appear slightly larger.

This is because carat in diamonds refers to weight, not physical size. Since CZ is denser, a 1 carat CZ has more mass packed into a smaller volume than a 1 carat lab grown diamond. What this means practically is that a CZ piece and a diamond piece can look similar in size even when the CZ is technically a lower carat weight.

It is the kind of thing that matters when you are comparing pieces across different materials and trying to make sense of what you are actually getting.

Certification Is What Separates a Diamond From a Lookalike

One of the clearest differences between lab grown diamonds and cubic zirconia lies in how they are recognized within the world of fine jewellery.

Lab grown diamonds are graded and certified by internationally recognised gemological laboratories such as IGI, GIA, and SGL using the same standards applied to mined diamonds. Their cut, colour, clarity, and carat are carefully evaluated and documented, giving you a transparent understanding of the diamond you are choosing.

Each certified lab grown diamond comes with a grading report that verifies its quality in precise, standardised terms. It is not simply sold on appearance alone, but assessed as a real diamond with measurable characteristics and long-term value.

Cubic zirconia does not go through this process because it is not classified as a diamond. There is no universal gemological grading system for CZ, and its quality is usually described only by the seller or manufacturer.

At Keemti, every lab grown diamond we use is certified because we believe the woman wearing it should know exactly what she is investing in: beautifully crafted, transparently certified, and designed for longevity. 

Lab Grown Diamonds vs Cubic Zirconia: Which Should You Choose?

• Choose CZ if you want affordable fashion jewellery that won't last long.

• Choose lab grown diamonds if you want fine jewellery designed for everyday wear and long-term durability.

Where Each One Actually Belongs

This is not about declaring one better than the other across every situation. 

Cubic zirconia has a clear and legitimate place in the world of accessories. It is affordable, widely available, and genuinely beautiful for fashion jewellery, trend-driven pieces, or occasions where sparkle matters more than longevity. There is no shame in owning and enjoying CZ pieces, and many people do, very intentionally.

But lab grown diamonds exist for a different kind of wearing. They are for the jewellery that becomes part of you. The solitaire that becomes part of your everyday rhythm. The pendant that someone who loves you chose carefully. The ring you wear through every version of yourself.

The Love Chronicle collection at Keemti is built for exactly this kind of meaning. Pieces designed for moments that matter and for the everyday moments in between, made from lab grown diamonds that will hold their brilliance as long as the memory they are attached to. 

The Everyday Edit collection is designed for the woman who never really takes her jewellery off, who moves through work, life, and everything in between wearing the same pieces because they fit every version of her day. For that kind of wearing, the difference between a lab grown diamond and CZ stops being abstract and becomes entirely practical.

The Real Difference Is Not Just Chemical

When people research lab grown diamonds and cubic zirconia comparisons, they are often asking a deeper question: Is what I'm getting real? Is it worth it? Will it last?

Lab grown diamonds are real diamonds. Not a workaround. Not a category of their own. Real, certified, scientifically verified diamonds that happen to have been created in a laboratory rather than mined from the earth. 

At Keemti, we work with lab grown diamonds because we believe fine jewellery should hold its beauty through every stage of life. Not just something that looks beautiful for a season, but something that stays. 

The decision between a lab grown diamond and CZ is ultimately a personal one, shaped by what you are buying the piece for, how you plan to wear it, and what you want it to mean over time.

But now you have what you need to make that decision with full clarity. And that, in itself, is the point.