Since cubic zirconia and diamonds have different weights, a 1 carat diamond will be a different size than a 1 carat CZ. Because of this, most people who want a CZ to approximate a certain size of diamond will use a conversion chart. It will show various sizes for cubic zirconia stones and what diamond weight carat they are equivalent to.
Remember that “carat” is a weight and not a size.
For example, if you wanted a CZ that looked like a 1 carat diamond, you would get a CZ that was 1.75 carats and 6.50mm.
This table is for round cut stones. Other shapes will be different, so verify sizing info with your jeweler:
| Size mm | CZ Carat Weight |
Diamond Carat Weight |
| 1.25 | 0.013 | 0.010 |
| 1.75 | 0.037 | 0.020 |
| 2.00 | 0.06 | 0.03 |
| 2.50 | 0.10 | 0.05 |
| 3.00 | 0.18 | 0.11 |
| 3.75 | 0.36 | 0.21 |
| 4.50 | 0.61 | 0.36 |
| 5.25 | 0.95 | 0.56 |
| 6.00 | 1.43 | 0.84 |
| 6.25 | 1.58 | 0.93 |
| 6.50 | 1.75 | 1.03 |
| 7.25 | 2.53 | 1.49 |
| 8.00 | 3.46 | 2.04 |
It is important to understand this so, in the event that you wanted a CZ that looked like a 1 carat diamond, for example, you don’t order a 1 carat cubic zirconia, because it would be smaller than what you wanted. According to the chart above, a 1 carat cubic zirconia would be equivalent in size to about a 0.57 carat diamond.