What is the Mohs scale of hardness?

The Mohs scale ranks minerals from 1 to 10 based on their ability to resist scratching. A Diamond is a 10 (the hardest natural substance), Sapphires/Rubies are 9, and Moissanite is 9.25. For an everyday engagement ring, we recommend stones with a Mohs rating of 8 or higher.

Is White Sapphire a good diamond alternative?

White Sapphire is very durable (9 on the Mohs scale) and affordable. However, it lacks the 'fire' (rainbow sparkle) of a diamond. It tends to look more like glass or a slightly cloudy diamond over time because it attracts dirt and oils quickly.

Home › Tools › Gemstone Comparison Tool

Gemstone & Diamond Comparison Tool

Not sure if you should choose a Diamond, Moissanite, or Sapphire? Compare the hardness, brilliance, and value of popular engagement ring center stones.

Select Gemstone 1

Select Gemstone 2

💎

Natural Diamond

Mohs Hardness 10

Brilliance (RI) 2.42

Price / Carat $$$$$

Everyday Wear Excellent

Pros

The hardest natural substance known.
Exceptional white sparkle.
Holds long-term value better than others.

Cons

The most expensive option by far.
Mining has ethical and environmental impacts.

✨

Moissanite

Mohs Hardness 9.25

Brilliance (RI) 2.65

Price / Carat $$

Everyday Wear Excellent

Pros

More brilliant (sparkly) than a diamond.
Extremely durable for daily wear.
A fraction of the cost of a diamond.

Cons

Has a "rainbow" disco-ball effect some dislike.
Virtually zero resale value.

💡 Hardness Tip: The Mohs scale is not linear. A Diamond (10) is actually 4 times harder than a Sapphire (9). For an engagement ring worn every day, we highly recommend stones with a Mohs rating of 8 or above to prevent scratching over time.

Key Metrics Explained

Mohs Hardness (Durability)

The Mohs scale ranks minerals from 1 to 10 based on their ability to scratch one another. Dust in the air contains quartz (Mohs 7), meaning any stone softer than a 7 will eventually be scratched just by wiping the dust off it. Diamonds are the hardest at 10, meaning only another diamond can scratch them.

Refractive Index (Brilliance)

The Refractive Index (RI) measures how much light bends when entering the stone. The higher the RI, the more brilliant and sparkly the gemstone appears. Moissanite has a higher RI (2.65) than Diamond (2.42), which gives it its intense "fire" or rainbow flashes.

Diamond vs. Moissanite vs. CZ

Diamonds have a balanced mix of white and colored light return. They are the gold standard for durability.

Moissanite is silicon carbide. It is almost as hard as a diamond (9.25) but exhibits much more rainbow-colored sparkle (fire), especially under sunlight.

Cubic Zirconia (CZ) is an inexpensive simulated diamond. However, it is soft (Mohs 8) and porous. Within a year or two of daily wear, it will absorb oils and become cloudy and scratched.

Frequently Asked Questions

No, Moissanite is a completely different gemstone (Silicon Carbide). However, it looks very similar to a diamond, is almost as hard, and actually has more brilliance (sparkle) than a diamond, making it the most popular diamond alternative.

There is no physical, chemical, or optical difference. They are both 100% crystallized carbon. The only difference is their origin (mined from the earth vs grown in a lab over a few weeks). Because lab diamonds have an infinite supply, they cost significantly less.

White Sapphire is very durable (9 on the Mohs scale) and affordable. However, it has a much lower Refractive Index than a diamond (1.77 vs 2.42), meaning it lacks the 'fire' (rainbow sparkle). It tends to look more like glass and requires frequent cleaning as dirt dulls it quickly.

Morganite is a beautiful peachy-pink stone, but it sits at 7.5 to 8 on the Mohs scale. This means it will eventually scratch and abrade over decades of daily wear. If you choose Morganite for an engagement ring, you must be prepared to replace or repolish the stone in the future.

Gemstone & Diamond Comparison Tool

Natural Diamond

Pros

Cons

Moissanite

Pros

Cons

Key Metrics Explained

Mohs Hardness (Durability)

Refractive Index (Brilliance)

Diamond vs. Moissanite vs. CZ

Frequently Asked Questions

Continue Reading