Moissanite vs. Cubic Zirconia (CZ) – Which Is the Better Diamond Simulant?
When it comes to engagement rings, diamonds are the traditional choice – but their sky-high prices put them out of reach for many couples. If you want that diamond look without the staggering price tag, the best solution is a diamond alternative.
Diamond alternatives mimic the appearance of real diamonds but differ in other ways. While natural zircon was the first diamond simulant, today’s most popular options are lab-created cubic zirconia (CZ) and moissanite.
So you might be wondering: Which of these diamond alternatives is better? Let’s compare the pros and cons of cubic zirconia versus moissanite to see which one comes out on top.
Moissanite vs. Cubic Zirconia – History and Origin
Natural moissanite was first discovered in 1893 by Henri Moissan in Arizona. Scientists believe these crystals were brought to Earth thousands of years ago by a meteorite impact, earning moissanite its romantic nicknames “stardust stone” and “space diamond.” Composed of silicon carbide (chemical formula SiC), moissanite has an extraordinary cosmic origin story.
In contrast, natural cubic zirconia wasn’t discovered until the 1930s. While CZ contains zirconium and oxygen (ZrO₂), moissanite consists of silicon and carbon – making its chemical composition notably closer to pure carbon diamonds than to cubic zirconia.
Both stones are exceptionally rare in nature. Today, all moissanite and cubic zirconia on the market are lab-created, ensuring ethical sourcing and consistent quality.
Winner: Moissanite. Its origin in the stars gives it an added romance and mystery and its composition is closer to diamond than CZ.
Moissanite vs. Cubic Zirconia – Durability
Diamond reigns supreme as the hardest gemstone with a perfect 10 on the Mohs scale. But moissanite comes remarkably close – as the second hardest jewelry-grade stone at 9.25 Mohs, it’s significantly more durable than most gemstones.
This exceptional hardness makes moissanite:
• Extremely resistant to scratches and abrasions
• Ideal for everyday wear in all jewelry types
• Particularly suited for engagement rings that face daily wear
Moissanite outperforms even diamond in heat resistance – maintaining its brilliance and shape when exposed to fire or high temperatures.
While cubic zirconia (CZ) is also durable with a hardness of 8-8.5 Mohs, moissanite demonstrates superior toughness (resistance to chipping/breaking):
• Moissanite toughness: 7.6 PSI
• CZ toughness: 2.4 PSI
→ Making moissanite over 3× more resistant to fractures
Winner: Moissanite. It is harder than CZ by 1.25 points and three times tougher.
Moissanite vs. Cubic Zirconia – Reaction to Dirt
Over time, both moissanite and cubic zirconia can develop a cloudy appearance from daily wear. Common culprits include:
• Household cleaners
• Makeup and skincare products
• Body oils
• Dust and dirt buildup
However, moissanite outperforms CZ in resisting this clouding effect:
→ Moissanite is more stain-resistant
→ CZ loses its luster faster and clouds more easily
→ CZ requires more frequent cleaning to maintain sparkle
Care Tips for Lasting Shine:
1. Clean moissanite monthly with mild soap and warm water
2. Clean CZ every 2-3 weeks for optimal brilliance
3. Avoid harsh chemicals with both stones
4. Store properly when not wearing
Winner: Moissanite. It is easier to clean and maintain.
Moissanite vs. Cubic Zirconia – Light Performance
The RI of a gemstone measures the amount of light that is bent as it goes through the gemstone and is an indicator of the gemstone’s brilliance.
Moissanite has a Refractive Index (RI) of 2.65 whereas diamond’s RI is lower at 2.42. Moissanite has an extremely high level of brilliance and excellent light performance. This is one reason it is a favorite in engagement rings as it has much higher brilliance and fire than a diamond.
The flip side is that moissanite often gives off a fiery flash of colors, which is noticeable especially under sunlight. This isn’t prominent in smaller moissanite stones, but the larger the stone is, the more pronounced this effect can become. Shoppers are often divided on how they feel about the rainbow effect, with some finding it gaudy and others loving the colorful sparkle. This rainbow effect is one main distinguishing feature between diamonds and moissanite.
Cubic zirconia has an RI 2.15 – 2.18, which is much lower than moissanite. Although CZ has a good amount of sparkle and brilliance, it is not at the depth of that of a moissanite. CZ can sometimes appear glassy and lacks the fire of diamonds and moissanites. Its sparkle is often described as being more superficial.
Winner: Moissanite wins for brilliance but may lose for the rainbow effect (depending on how you feel about it). We’ll let you decide this one.
The Final Verdict…
Although CZ is a more affordable choice, we would have to choose moissanite as the better diamond simulant of the two, owing to its durability, brilliance and value.
In terms of prestige and class, nothing can take the place of a diamond, but moissanite comes close. CZ, unfortunately, will always be considered inexpensive and of little value.
When deciding between the two, lay down your budget and your priorities. And chances are no one would ever know the difference. At a glance, diamonds, moissanite and cubic zirconia all look alike.