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A lab-grown diamond is a real, permanent diamond; cubic zirconia (CZ) is an inexpensive lab-made simulant that looks sparkly at first but clouds and scratches over time. They sit at opposite ends of the spectrum. Here is the honest comparison.
Key takeaways
- A lab-grown diamond is a real diamond (Mohs 10); CZ is a simulant (zirconium dioxide, around Mohs 8).
- CZ is the cheapest diamond look-alike but is not durable for a lifetime ring.
- CZ scratches and clouds with everyday wear, and is typically replaced over time.
- CZ throws more rainbow fire and can look glassy or 'too perfect'.
- For a forever ring, a lab-grown diamond is the lasting choice; CZ suits costume or temporary pieces.
What is cubic zirconia?
Cubic zirconia is a man-made crystal (zirconium dioxide) created as an inexpensive diamond simulant. It is colourless, very sparkly when new, and extremely affordable — which makes it popular for fashion jewellery, travel pieces and placeholders. But it is not a diamond, and it does not wear like one.
What is a lab-grown diamond?
A lab-grown diamond is chemically and physically identical to a mined diamond — pure carbon, the hardest material there is, graded on the 4Cs by IGI or GIA. It is a real diamond grown in a lab rather than the earth. See how they are made and lab-grown vs mined.
Every centre diamond is Triple Excellent, D–E, VVS and at least three carats — the hard calls are made for you.
Design your ringSide by side
| Lab-grown diamond | Cubic zirconia | |
|---|---|---|
| What it is | Real diamond (carbon) | Simulant (zirconium dioxide) |
| Hardness (Mohs) | 10 (hardest) | ~8 |
| Durability | A lifetime; never clouds | Scratches and clouds over time |
| Look | Balanced diamond brilliance | Glassy, heavy rainbow fire |
| Certification | IGI / GIA on the 4Cs | None |
| Price | Real diamond, far below mined | Lowest — costume-level |
How they age
This is the real difference. A diamond — mined or lab-grown — stays brilliant forever. Cubic zirconia is softer and more porous, so it picks up scratches and absorbs oils, gradually turning cloudy or grey, usually within a few years of daily wear. CZ jewellery is meant to be replaced; a diamond ring is meant to be kept.
The look
New CZ sparkles, but it throws much more coloured 'fire' than a diamond and can read glassy or unnaturally flawless up close. A diamond's balanced white-and-coloured brilliance is what the eye recognises as the real thing.
Which should you choose?
For a costume piece, a travel stand-in, or a temporary placeholder, CZ is perfectly sensible — cheap and cheerful. For an engagement ring meant to last a lifetime, a lab-grown diamond is a real diamond at a fraction of mined prices, and it will look as brilliant in fifty years as today. Montare works only in real, certified lab-grown diamonds — D–E, VVS1–VVS2, Triple Excellent, three carats minimum, IGI certified.
Design your ring in minutes. Every centre diamond is D–E colour, VVS clarity, Triple Excellent cut and at least three carats — IGI certified, made to order in Toronto.
Open the ring builder →Frequently asked questions
Is cubic zirconia a diamond?
No. CZ is a simulant made of zirconium dioxide. A lab-grown diamond, by contrast, is a real diamond — pure carbon.
Does cubic zirconia last?
Not like a diamond. CZ is softer and tends to scratch and cloud within a few years of daily wear, so it is usually replaced rather than kept.
Can you tell cubic zirconia from a diamond?
Often, yes — CZ throws heavier rainbow fire and can look glassy, and over time it clouds. A diamond stays clear and balanced.
Is lab-grown diamond worth it over CZ?
For a lasting ring, yes — a lab-grown diamond is a real, permanent diamond at far below mined prices. CZ is best for temporary or costume pieces.
Choose a real diamond. Build one in the ring builder or book a consultation.
The Montare standard
Lab-grown · D–E colour · VVS clarity · Triple Excellent · 3ct minimum · IGI certified
Every ring is made to order in Toronto and backed by our lifetime setting upgrade, with free, fully insured shipping.
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