Cubic zirconia size chart: carat to mm for every shape
By HeyGema™ · Updated
In short
A 1 carat round cubic zirconia measures about 5.5 mm across, against 6.5 mm for a 1 carat diamond. Cubic zirconia is denser than diamond (5.80 against 3.52), so it packs more weight into less space and faces up 15% narrower for the same weight.
- 5.5 mm1 carat round cubic zirconia
- 5.80density, g/cm3
- 8 to 8.5hardness, Mohs
Carat to mm calculator
About 5.5 x 5.5 mm
An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.
Cubic zirconia size chart: carat to mm
Face-up length and width in mm of a well-cut cubic zirconia at each weight and shape. Cubic zirconia is denser than diamond (5.80 against 3.52), so it packs more weight into less space and faces up 15% narrower for the same weight.
| Weight | Round | Oval | Cushion | Emerald cut | Pear | Princess |
|---|---|---|---|---|---|---|
| 0.25 ct | 3.4 | 4.3 x 2.93 | 2.99 x 2.99 | 3.7 x 2.67 | 4.5 x 2.93 | 2.93 x 2.93 |
| 0.5 ct | 4.3 | 5.4 x 3.7 | 3.8 x 3.8 | 4.7 x 3.4 | 5.7 x 3.7 | 3.7 x 3.7 |
| 0.75 ct | 5.0 | 6.2 x 4.2 | 4.3 x 4.3 | 5.4 x 3.8 | 6.5 x 4.2 | 4.2 x 4.2 |
| 1 ct | 5.5 | 6.8 x 4.7 | 4.7 x 4.7 | 5.9 x 4.2 | 7.2 x 4.7 | 4.7 x 4.7 |
| 1.5 ct | 6.3 | 7.8 x 5.3 | 5.4 x 5.4 | 6.8 x 4.8 | 8.2 x 5.3 | 5.3 x 5.3 |
| 2 ct | 6.9 | 8.5 x 5.9 | 6.0 x 6.0 | 7.5 x 5.3 | 9.1 x 5.9 | 5.9 x 5.9 |
| 3 ct | 7.9 | 9.8 x 6.7 | 6.8 x 6.8 | 8.5 x 6.1 | 10.4 x 6.7 | 6.7 x 6.7 |
| 4 ct | 8.7 | 10.8 x 7.4 | 7.5 x 7.5 | 9.4 x 6.7 | 11.4 x 7.4 | 7.4 x 7.4 |
| 5 ct | 9.3 | 11.6 x 8.0 | 8.1 x 8.1 | 10.1 x 7.2 | 12.3 x 8.0 | 8.0 x 8.0 |
| 10 ct | 11.8 | 14.6 x 10.0 | 10.2 x 10.2 | 12.8 x 9.1 | 15.5 x 10.0 | 10.0 x 10.0 |
Length x width in mm. A round stone shows one number, its diameter.
mm to carat for a round cubic zirconia
If you know the size, this is the weight. Measure across the widest point of the stone, face up.
- 4 mm
- Weight: 0.39 ct
- 5 mm
- Weight: 0.77 ct
- 6 mm
- Weight: 1.33 ct
- 7 mm
- Weight: 2.11 ct
- 8 mm
- Weight: 3.14 ct
- 9 mm
- Weight: 4.48 ct
- 10 mm
- Weight: 6.14 ct
- 12 mm
- Weight: 10.61 ct
Cubic zirconia against diamond
How wide a round cubic zirconia is next to a round diamond of the same weight.
- 0.5 ct
- Cubic zirconia: 4.3 mm
- Diamond: 5.1 mm
- Difference: -0.8 mm
- 1 ct
- Cubic zirconia: 5.5 mm
- Diamond: 6.5 mm
- Difference: -1.0 mm
- 2 ct
- Cubic zirconia: 6.9 mm
- Diamond: 8.1 mm
- Difference: -1.2 mm
- 3 ct
- Cubic zirconia: 7.9 mm
- Diamond: 9.3 mm
- Difference: -1.4 mm
- 5 ct
- Cubic zirconia: 9.3 mm
- Diamond: 11.0 mm
- Difference: -1.7 mm
Cubic zirconia properties
- Density used in the charts
- Value: 5.80 g/cm3 (range 5.6 to 6.0)
- Hardness (Mohs)
- Value: 8 to 8.5
- Refractive index
- Value: 2.15 to 2.18
Much denser than diamond, so a stone of the same weight is much smaller. It is sold by size in mm.