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Moissanite Carat Size Chart: How Many Millimeters Is a 1, 2 or 3 Carat Moissanite?
Quick Answer: Moissanite is usually sold by size in millimeters or by diamond-equivalent weight (DEW). A 6.5 mm round moissanite looks like a 1 carat diamond, an 8 mm round looks like 2 carats, and a 9.3 mm round looks like 3 carats. Moissanite is about 10% lighter than diamond, so its actual weight is slightly lower than the carat size it looks like.
Key Takeaways
- Moissanite is sized by millimeters or diamond-equivalent weight (DEW).
- Moissanite has a density of about 3.21 g/cm³ compared with 3.52 g/cm³ for diamond, so it weighs less for the same size.
- The most popular engagement ring sizes are 1 to 2 carats (6.5 to 8 mm round).
What Is Diamond-Equivalent Weight?
Carat is a measure of weight, not size. Because moissanite is lighter than diamond, a moissanite and a diamond of the same size do not weigh the same. To make shopping simple, moissanite is described by the carat weight a diamond of the same size would have. This is called diamond-equivalent weight, or DEW.
Round Moissanite Size Chart
| Looks like (DEW) | Diameter (mm) |
|---|---|
| 0.25 ct | 4.0 mm |
| 0.50 ct | 5.0 mm |
| 0.75 ct | 5.8 mm |
| 1.00 ct | 6.5 mm |
| 1.50 ct | 7.4 mm |
| 2.00 ct | 8.0 mm |
| 2.50 ct | 8.7 mm |
| 3.00 ct | 9.3 mm |
| 4.00 ct | 10.2 mm |
| 5.00 ct | 11.0 mm |
Fancy Shape Size Chart
Shaped stones are measured length by width. Approximate sizes:
| Looks like (DEW) | Oval | Emerald / Radiant | Pear |
|---|---|---|---|
| 1 ct | 7 x 5 mm | 7 x 5 mm | 8 x 5 mm |
| 2 ct | 9 x 7 mm | 8 x 6 mm | 10 x 6 mm |
| 3 ct | 10 x 8 mm | 9 x 7 mm | 12 x 7 mm |
How Big Should My Stone Be?
- 1 ct (6.5 mm): classic, elegant and easy to wear daily.
- 2 ct (8 mm): a statement look that still feels balanced on most hands.
- 3 ct and up: bold and glamorous. Moissanite makes larger stones affordable.
Elongated shapes such as oval, pear and marquise look larger than rounds of the same weight because they cover more of the finger.
Frequently Asked Questions
What size is a 1 carat moissanite?
A 1 carat diamond-equivalent round moissanite is about 6.5 mm across. Its actual weight is around 0.88 carats because moissanite is lighter than diamond.
Does moissanite weigh the same as diamond?
No. Moissanite is about 10% less dense than diamond, so a moissanite of the same size weighs slightly less.
What is the most popular moissanite engagement ring size?
Between 1 and 2 carats diamond-equivalent, or about 6.5 to 8 mm for a round stone.
Find your perfect size in our engagement ring collection.