Finding the right stone size starts with understanding millimeter-to-carat conversions. This moissanite size chart provides accurate mm-to-carat measurements for every popular cut, helping you compare sizes and choose the perfect stone for your ring. Whether you are shopping for a 1-carat round or a 3-carat oval, this chart gives you the exact dimensions you need.
How to Use This Moissanite Size Chart
Moissanite is sold using Diamond Equivalent Weight (DEW), which tells you the visual size relative to diamond. However, the most accurate way to compare stones is by their millimeter measurements. This moissanite size chart lists both DEW and millimeter dimensions for each cut.
Key terms:
- DEW: Diamond Equivalent Weight—visual size relative to diamond
- mm: Millimeter—the physical measurement of the stone
- Actual weight: The true carat weight of the moissanite stone
Round Brilliant Moissanite Size Chart
| DEW | Diameter (mm) | Actual Weight | Depth (mm) |
|---|---|---|---|
| 0.25 ct | 4.1 | 0.22 ct | 2.5 |
| 0.33 ct | 4.5 | 0.29 ct | 2.7 |
| 0.50 ct | 5.0 | 0.44 ct | 3.0 |
| 0.75 ct | 5.8 | 0.66 ct | 3.5 |
| 1.00 ct | 6.5 | 0.88 ct | 3.9 |
| 1.25 ct | 7.0 | 1.10 ct | 4.2 |
| 1.50 ct | 7.4 | 1.32 ct | 4.4 |
| 1.75 ct | 7.8 | 1.54 ct | 4.7 |
| 2.00 ct | 8.0 | 1.76 ct | 4.8 |
| 2.50 ct | 8.5 | 2.20 ct | 5.1 |
| 3.00 ct | 9.0 | 2.64 ct | 5.4 |
| 3.50 ct | 9.5 | 3.08 ct | 5.7 |
| 4.00 ct | 10.0 | 3.52 ct | 6.0 |
Oval Moissanite Size Chart
| DEW | Length (mm) | Width (mm) | Actual Weight |
|---|---|---|---|
| 0.50 ct | 6.0 | 4.0 | 0.44 ct |
| 0.75 ct | 6.7 | 4.5 | 0.66 ct |
| 1.00 ct | 7.5 | 5.0 | 0.88 ct |
| 1.25 ct | 7.9 | 5.3 | 1.10 ct |
| 1.50 ct | 8.5 | 5.7 | 1.32 ct |
| 2.00 ct | 9.5 | 6.4 | 1.76 ct |
| 2.50 ct | 10.3 | 6.9 | 2.20 ct |
| 3.00 ct | 11.0 | 7.4 | 2.64 ct |
Cushion Moissanite Size Chart
| DEW | Length (mm) | Width (mm) | Actual Weight |
|---|---|---|---|
| 0.50 ct | 4.5 | 4.5 | 0.44 ct |
| 0.75 ct | 5.2 | 5.2 | 0.66 ct |
| 1.00 ct | 5.8 | 5.8 | 0.88 ct |
| 1.25 ct | 6.2 | 6.2 | 1.10 ct |
| 1.50 ct | 6.6 | 6.6 | 1.32 ct |
| 2.00 ct | 7.2 | 7.2 | 1.76 ct |
| 2.50 ct | 7.7 | 7.7 | 2.20 ct |
| 3.00 ct | 8.2 | 8.2 | 2.64 ct |
Pear Moissanite Size Chart
| DEW | Length (mm) | Width (mm) | Actual Weight |
|---|---|---|---|
| 0.50 ct | 6.0 | 4.0 | 0.44 ct |
| 0.75 ct | 6.8 | 4.6 | 0.66 ct |
| 1.00 ct | 7.5 | 5.0 | 0.88 ct |
| 1.50 ct | 8.7 | 5.8 | 1.32 ct |
| 2.00 ct | 9.5 | 6.4 | 1.76 ct |
| 2.50 ct | 10.4 | 6.9 | 2.20 ct |
| 3.00 ct | 11.2 | 7.5 | 2.64 ct |
Princess Moissanite Size Chart
| DEW | Length (mm) | Width (mm) | Actual Weight |
|---|---|---|---|
| 0.50 ct | 4.4 | 4.4 | 0.44 ct |
| 0.75 ct | 5.1 | 5.1 | 0.66 ct |
| 1.00 ct | 5.7 | 5.7 | 0.88 ct |
| 1.25 ct | 6.1 | 6.1 | 1.10 ct |
| 1.50 ct | 6.5 | 6.5 | 1.32 ct |
| 2.00 ct | 7.1 | 7.1 | 1.76 ct |
| 2.50 ct | 7.6 | 7.6 | 2.20 ct |
| 3.00 ct | 8.1 | 8.1 | 2.64 ct |
Emerald Moissanite Size Chart
| DEW | Length (mm) | Width (mm) | Actual Weight |
|---|---|---|---|
| 0.50 ct | 5.5 | 3.7 | 0.44 ct |
| 0.75 ct | 6.2 | 4.1 | 0.66 ct |
| 1.00 ct | 6.8 | 4.5 | 0.88 ct |
| 1.50 ct | 7.7 | 5.1 | 1.32 ct |
| 2.00 ct | 8.5 | 5.7 | 1.76 ct |
| 2.50 ct | 9.2 | 6.1 | 2.20 ct |
| 3.00 ct | 9.8 | 6.5 | 2.64 ct |
Marquise Moissanite Size Chart
| DEW | Length (mm) | Width (mm) | Actual Weight |
|---|---|---|---|
| 0.50 ct | 7.0 | 3.5 | 0.44 ct |
| 0.75 ct | 8.0 | 4.0 | 0.66 ct |
| 1.00 ct | 9.0 | 4.5 | 0.88 ct |
| 1.50 ct | 10.3 | 5.2 | 1.32 ct |
| 2.00 ct | 11.4 | 5.7 | 1.76 ct |
| 2.50 ct | 12.3 | 6.2 | 2.20 ct |
| 3.00 ct | 13.1 | 6.6 | 2.64 ct |
How to Measure Your Stone
If you already have a ring and want to determine the carat size, measure the stone in millimeters:
- Use a caliper or mm ruler for the most accurate measurement
- Measure diameter for round stones (across the widest point)
- Measure length and width for fancy shapes
- Compare to the charts above to find your DEW
Tips for Using This Moissanite Size Chart
1. Focus on Millimeters, Not Carat Weight
Millimeter measurements are the most accurate way to understand a stone's visual size. Two stones with the same DEW may have slightly different millimeter dimensions depending on the manufacturer's cutting standards.
2. Consider Cut Depth
Depth affects how a stone sits in its setting. Deeper stones sit higher, while shallower stones sit lower. Round brilliant moissanite typically has a depth of 60–62% of its diameter.
3. Account for Setting Impact
Halo settings add approximately 1–2mm of visual diameter around the center stone. A 6.5mm (1.0 ct) center stone in a halo setting can look like an 8.5mm (2.0 ct) stone.
4. Compare Multiple Cuts
The same carat weight looks different across cuts. A 1.0 ct oval (7.5mm long) appears larger than a 1.0 ct round (6.5mm diameter) because of its elongated shape. See our moissanite carat size guide for more comparisons.
Frequently Asked Questions
How many mm is a 1 carat moissanite?
A 1-carat moissanite (DEW) in round brilliant cut measures 6.5mm in diameter. For other cuts, see the charts above. Learn more in our 1 carat moissanite guide.
How many mm is a 2 carat moissanite?
A 2-carat moissanite (DEW) in round brilliant cut measures 8.0mm in diameter. See our 2 carat moissanite guide.
How do I convert mm to carat for moissanite?
Use the charts in this moissanite size chart to find the DEW that corresponds to your stone's millimeter measurement. Remember that moissanite actual weight is approximately 12% less than DEW. For more on this, read our moissanite carat vs diamond carat guide.
Does the same mm size look the same across brands?
Generally yes, but minor variations of 0.1–0.2mm can occur due to different cutting standards. Always verify the exact millimeter dimensions with your retailer.
Conclusion
This moissanite size chart provides the millimeter-to-carat conversions you need to choose the perfect stone. By focusing on millimeter measurements rather than just carat weight, you can accurately compare sizes across cuts and make an informed decision. Whether you choose a 6.5mm round or an 11mm oval, understanding the dimensions ensures your ring looks exactly as you envision.
Ready to find your perfect size? Explore our complete moissanite carat size guide, check finger coverage recommendations, and shop our collection today.