Zirconia vs Real Diamond vs Lab Grown Diamond: What's the Difference?

Walk into any jewellery store — or browse online — and you will quickly encounter three types of sparkling stones that look remarkably similar: cubic zirconia, natural diamonds, and lab grown diamonds. For the untrained eye, telling them apart is nearly impossible. Yet they are fundamentally different materials with very different properties, prices, and purposes.

Understanding the differences is not just academic — it directly affects what you buy, what you pay, and what you get. This complete guide breaks down all three side by side, so you can shop with full clarity and confidence.

What Is Cubic Zirconia (CZ)?

Cubic zirconia — often shortened to CZ — is a synthetic, lab-created material made from zirconium dioxide (ZrO₂). It was first developed for industrial laser use in the Soviet Union in the 1970s before being commercialised as a diamond simulant in 1976.

The key word here is simulant — cubic zirconia is not a diamond and does not have the same chemical composition or structure. It is a completely different material that is designed to look like a diamond. This distinguishes it fundamentally from a lab grown diamond, which is an actual diamond.

How Is Cubic Zirconia Made?

CZ is produced through a process called skull crucible melting. Zirconium oxide powder is combined with a stabiliser (usually yttrium or calcium oxide) and melted at extremely high temperatures (around 2,750°C). The material is then slowly cooled to form large crystals, which are cut and polished into faceted stones.

The process is fast, inexpensive, and highly scalable — which is why CZ can be produced in virtually unlimited quantities at very low cost.

Key Properties of Cubic Zirconia

•        Chemical composition: Zirconium dioxide (ZrO₂) — not carbon

•        Hardness: 8–8.5 on Mohs scale (diamonds are 10)

•        Refractive index: 2.15–2.18 (slightly higher than diamond's 2.42)

•        Dispersion: 0.058–0.066 — higher than diamond, producing more 'rainbow fire'

•        Density: ~5.6–6.0 g/cm³ — noticeably heavier than diamond (3.52 g/cm³)

•        Durability: Less hard than diamond — scratches and chips over time with daily wear

•        Cost: A fraction of the price — typically ₹50–₹500 per carat for standard CZ

What Is a Real (Natural) Diamond?

A natural diamond is pure crystallised carbon formed deep within the earth's mantle over 1–3 billion years under extreme heat (1,300°C+) and pressure (45,000+ atmospheres). Volcanic eruptions carry diamond-bearing rock (kimberlite) to the surface, where it is mined.

Diamonds are the hardest natural material on earth — scoring a perfect 10 on the Mohs hardness scale — and possess unmatched optical properties that give them their legendary brilliance, fire, and scintillation.

Key Properties of Natural Diamond

•        Chemical composition: Pure carbon (C) in cubic crystal structure

•        Hardness: 10 on Mohs scale — hardest natural material known

•        Refractive index: 2.417 — exceptional light bending

•        Dispersion: 0.044 — produces classic diamond fire

•        Density: 3.52 g/cm³

•        Durability: Extraordinary — resistant to scratching, chipping, and chemical damage

•        Cost: High — driven by rarity, geological scarcity, and market value

•        Resale value: Significant — natural diamonds retain and appreciate in value over time

What Is a Lab Grown Diamond?

A lab grown diamond is a real diamond — chemically, physically, and optically identical to a natural diamond — but grown in a laboratory using either HPHT (High Pressure High Temperature) or CVD (Chemical Vapour Deposition) technology. It is pure carbon in the same cubic crystal structure as a natural diamond.

The critical distinction: a lab grown diamond is a diamond. A cubic zirconia is not. This is the most important thing to understand in this entire comparison.

Key Properties of Lab Grown Diamond

•        Chemical composition: Pure carbon (C) — identical to natural diamond

•        Hardness: 10 on Mohs scale — identical to natural diamond

•        Refractive index: 2.417 — identical to natural diamond

•        Dispersion: 0.044 — identical to natural diamond

•        Density: 3.52 g/cm³ — identical to natural diamond

•        Durability: Same as natural diamond — extraordinary

•        Cost: 40–60% less than natural diamonds of comparable quality

•        Resale value: Lower than natural diamonds — see our detailed guide on Lab Grown Diamonds Resale Value

At a Glance: The Three Stones

  Diamond simulant — looks like diamond, is not diamond

  Earth-formed pure carbon — the original

  Laboratory-grown pure carbon — real diamond, different origin

Full Comparison: Cubic Zirconia vs Natural Diamond vs Lab Grown Diamond

Can You Tell Them Apart Just by Looking?

This is the question most people ask first — and the answer is nuanced.

Cubic Zirconia vs Diamond — Can You Tell?

With the naked eye, a high-quality CZ can be very convincing. However, there are tells an experienced eye can spot:

•        Too much fire: CZ has higher dispersion than diamond, producing more colourful rainbow flashes — sometimes described as 'too sparkly' or artificial-looking, especially in bright light.

•        Weight: CZ is noticeably heavier than diamond for the same size stone — you can feel the difference when holding loose stones.

•        Warmth test: Diamonds conduct heat rapidly and feel cold initially. CZ retains heat more slowly — a trained jeweller can detect this.

•        Scratch test: CZ scratches. Over time, the surface of a CZ stone becomes dulled and cloudy. A diamond remains perfectly sharp-edged indefinitely.

•        Breath test: Fog from breath disappears almost instantly from a diamond (excellent heat conductor) but lingers on CZ.

Lab Grown Diamond vs Natural Diamond — Can You Tell?

With standard tools and the naked eye — no. Lab grown diamonds are visually indistinguishable from natural diamonds. Even professional gemologists with loupes cannot reliably tell them apart without specialised equipment (HPHT/CVD detection machines or advanced spectroscopy).

The only reliable ways to differentiate are:

•        Advanced spectroscopic analysis at a gemological laboratory

•        The diamond's certification — all reputable lab grown diamonds are clearly marked as laboratory-grown on their IGI or GIA certificate

•        Microscopic inclusion pattern analysis — CVD diamonds may show specific layered growth patterns under high magnification

Which Should You Choose? A Buyer's Guide

Choose Cubic Zirconia If:

•        You want a sparkling stone for fashion jewellery or costume pieces at minimal cost

•        You frequently change styles and do not want to invest heavily in any single piece

•        You are buying for a child or as a short-term gift where longevity is not the priority

•        You want to try out a jewellery style before investing in a real diamond version

Choose a Natural Diamond If:

•        You are buying for a significant occasion — engagement, anniversary, heirloom — where emotional and material value both matter

•        Long-term resale value or investment potential is important to you

•        You value the geological rarity and billions-of-years origin story of the stone

•        You want a piece that can be passed down through generations

Choose a Lab Grown Diamond If:

•        You want a real diamond but at a significantly lower price point

•        You can afford a larger or higher-quality stone within your budget than natural diamonds would allow

•        Ethical sourcing and avoiding mining is important to you

•        You are buying for beauty and wearability rather than investment resale

•        You want full certification and gemological grading with the confidence of a genuine diamond

CZ vs Lab Diamond vs Natural Diamond in Jewellery Settings

All three stones are used across the jewellery spectrum — but each has a natural fit:

•        CZ in silver jewellery — CZ is widely set in silver rings as an affordable fashion choice. The combination looks beautiful and is accessible to all budgets — ideal for everyday style pieces.

•        Lab grown diamonds in silver settings — Setting a lab grown diamond in a silver pendant or sterling silver ring gives you genuine diamond quality at a price point that makes fine jewellery widely accessible. An increasingly popular choice.

•        Natural diamonds in precious metal settings — Natural diamonds are typically set in gold or platinum for investment and heirloom pieces. However, natural diamond silver necklaces with accent stones are a beautiful and more accessible entry into natural diamond jewellery.

•        Moissanite — Worth mentioning: moissanite is another diamond simulant (silicon carbide) that sits between CZ and diamond in hardness and price, with its own unique optical properties. It is a popular middle-ground choice.

Buying Zirconia and Diamond Jewellery in India — What to Know

India has one of the world's largest fine jewellery markets, and all three stone types — CZ, lab grown diamond, and natural diamond — are widely available. Here is what Indian buyers should keep in mind:

•        Hallmarking matters: Always verify the metal purity of the setting. Look for BIS hallmarks on silver and gold. The stone type should be clearly disclosed by the seller.

•        Ask for certification: Any diamond — natural or lab grown — should come with an IGI, GIA, or SGL certificate. CZ is not gemologically certified. If a seller claims CZ is 'diamond-grade' without a certificate, be cautious.

•        'American Diamond' is CZ: In India, cubic zirconia is widely marketed as 'American Diamond' — a trade term with no official standing. It is not a diamond. It is CZ. This labelling can confuse buyers who assume they are purchasing a real diamond.

•        Swiss Zircon vs Cubic Zirconia: 'Swiss Zircon' is another trade name for high-quality CZ — not a natural zircon gemstone. Both are CZ variants with no diamond properties.

•        Lab grown pricing in India: Lab grown diamonds have become significantly more accessible in India over the past few years. A 1-carat IGI-certified lab grown diamond can now be purchased for a fraction of the cost of an equivalent natural diamond.

Frequently Asked Questions

Is cubic zirconia worth anything?

As a gemstone investment — no. CZ has negligible resale value because it can be produced in unlimited quantities at very low cost. However, as a fashion accessory, it offers excellent visual value for money. Its worth is in its appearance, not its material rarity.

Will cubic zirconia pass a diamond tester?

No. Standard thermal diamond testers measure heat conductivity. CZ conducts heat differently to diamond and will not pass as diamond on a thermal tester. Modern multi-testers that also test electrical conductivity can distinguish even moissanite from diamond.

Is a lab grown diamond better than CZ?

For any purpose beyond fashion jewellery — yes, significantly. A lab grown diamond is a real diamond with the same hardness, brilliance, and durability as a natural diamond. It will never scratch, cloud, or dull. A CZ will gradually lose its sparkle with daily wear. For fine jewellery, lab grown diamond is a far superior choice.

Does cubic zirconia tarnish or turn yellow?

CZ does not tarnish the way silver does, but it can cloud, scratch, and dull over time as micro-scratches accumulate on its surface through daily wear. It can also take on a slightly yellowed or hazy appearance after prolonged use. This is why CZ is better suited to occasional-wear fashion pieces than everyday fine jewellery.

Can lab grown diamonds be used as a substitute for natural diamonds in engagement rings?

Absolutely — and increasingly they are. Lab grown diamonds are real diamonds with identical physical properties. Many couples choose lab grown for engagement rings specifically because they can afford a larger or higher-quality stone within their budget. The only difference is origin — the beauty, durability, and symbolic weight are identical.

What is 'American Diamond' — is it a real diamond?

No. 'American Diamond' is a marketing term used in India for cubic zirconia (CZ). It has no official gemological standing and is not a diamond in any sense. It is a synthetic zirconium dioxide simulant. Buyers should be aware of this terminology to avoid confusion when purchasing jewellery.

Final Thoughts

The three stones at the centre of this guide — cubic zirconia, natural diamonds, and lab grown diamonds — look alike but are fundamentally different in material, durability, value, and purpose. Understanding the difference is not about being a gemologist; it is about being an informed buyer.

To summarise simply:

•        Cubic zirconia — a beautiful, affordable simulant that is not a diamond. Great for fashion jewellery, not for investment or long-term fine jewellery.

•        Natural diamond — the original, earth-formed diamond with unmatched rarity, durability, and long-term value. The choice for heirlooms and investment.

•        Lab grown diamond — a real diamond, grown in weeks instead of billions of years. The smart choice for buyers who want genuine diamond quality with a more accessible price tag and a cleaner supply chain.

Whatever stone speaks to you — the affordable sparkle of CZ, the timeless prestige of a natural diamond, or the modern value of a lab grown — make sure you know exactly what you are buying. Always ask for certification on diamonds, verify BIS hallmarks on your metal settings, and buy from transparent, reputable brands.

Also Read

•        How Are Lab Grown Diamonds Made? The Complete Guide to CVD & HPHT

•        Lab Grown Diamonds Resale Value Explained: Are They Worth Buying?

•        Is 925 Silver 100% Pure? Everything You Need to Know About Sterling Silver

•        White Gold vs Yellow Gold vs Rose Gold: Which Is Best for You?

•        How to Identify Pure Silver: 7 Proven Methods