Cushion cut diamonds, with their romantic and vintage allure, have been a favorite for more than a century. Known for their rounded corners and larger facets, these stones have a unique appeal that combines the brilliance of a round cut with the traditional aspect of a square cut. When selecting a cushion cut diamond, it’s crucial to understand how the size, measured in millimeters (mm), translates to carat weight, and how this impacts overall appearance and value.
The Charm of Cushion Cut Diamonds
The cushion cut’s enduring popularity is rooted in its ability to offer a soft yet radiant look that’s versatile enough for various settings. Renowned jewelry historian Elizabeth Taylor notes, “The cushion cut has been beloved throughout different eras, evolving with cutting techniques but always keeping its signature warmth and charm.”
Sizing Up the Cushion Cut
Unlike round diamonds, cushion cut diamonds come in a range of dimensions and ratios, which can make sizing a bit more complex. The aspect ratio (length divided by width) will determine whether a diamond appears more square or rectangular. According to diamond cutter expert Josephine Cut, “A classic cushion cut diamond will have an aspect ratio between 1.00 and 1.09 for a square shape, while more elongated versions will range from 1.15 onwards.”
Cushion Cut Diamond Size Chart: MM to Carat Weight
Here is a size chart that correlates typical dimensions in millimeters to their approximate carat weights. This chart should serve as a general guide, as the actual carat weight can vary depending on the specific dimensions and proportions of the diamond.
| Length x Width (mm) | Approximate Carat Weight |
|---|---|
| 1.0 x 1.0 mm | 0.005 ct |
| 1.5 x 1.5 mm | 0.015 ct |
| 2.0 x 2.0 mm | 0.03 ct |
| 2.5 x 2.5 mm | 0.06 ct |
| 3.0 x 3.0 mm | 0.10 ct |
| 3.5 x 3.5 mm | 0.17 ct |
| 4.0 x 4.0 mm | 0.25 ct |
| 4.5 x 4.5 mm | 0.35 ct |
| 5.0 x 5.0 mm | 0.50 ct |
| 5.5 x 5.5 mm | 0.66 ct |
| 6.0 x 6.0 mm | 0.85 ct |
| 6.5 x 6.5 mm | 1.00 ct |
| 7.0 x 7.0 mm | 1.25 ct |
| 7.5 x 7.5 mm | 1.50 ct |
| 8.0 x 8.0 mm | 2.00 ct |
| 8.5 x 8.5 mm | 2.50 ct |
| 9.0 x 9.0 mm | 3.00 ct |
| 9.5 x 9.5 mm | 3.50 ct |
| 10.0 x 10.0 mm | 4.00 ct |
| 10.5 x 10.5 mm | 4.50 ct |
| 11.0 x 11.0 mm | 5.00 ct |
| 11.5 x 11.5 mm | 5.50 ct |
| 12.0 x 12.0 mm | 6.00 ct |
| 12.5 x 12.5 mm | 6.50 ct |
| 13.0 x 13.0 mm | 7.00 ct |
| 13.5 x 13.5 mm | 7.50 ct |
| 14.0 x 14.0 mm | 8.00 ct |
| 14.5 x 14.5 mm | 8.50 ct |
| 15.0 x 15.0 mm | 9.00 ct |
| 15.5 x 15.5 mm | 9.50 ct |
| 16.0 x 16.0 mm | 10.00 ct |
The carat weights in the table are approximate and assume a certain depth and cut quality. The weight can fluctuate based on these factors.
Understanding the Impact of Ratio and Cut
Aspect Ratio
The aspect ratio will impact how the diamond is perceived in size. Square cushions often look smaller than elongated ones, even if they have the same carat weight, due to the difference in the top surface area that is visible when the stone is set into a ring.
Cut Quality
A cushion cut’s beauty lies in its brilliance and fire. The quality of the cut determines how the light is reflected within the diamond. A higher-quality cut will ensure that the stone looks its best, regardless of its size in mm or carat weight.
Depth and Table
The depth percentage (depth of the diamond divided by its overall size) and table percentage (width of the top facet of the diamond compared to the overall width of the stone) are critical in a cushion cut diamond. The right balance will ensure maximum brilliance and perceived size.
Concluding Thoughts
When choosing a cushion cut diamond, it’s not just the mm size or carat weight that matters—it’s about the harmony between size, cut quality, and proportions that creates the perfect stone for you. A detailed understanding of these aspects, alongside expert advice, will lead to a selection that captures the essence of what you desire.
Expert gemologist and certified appraiser Sarah Lumière advises, “Always view the diamond in person if possible. Beyond the numbers, the way a diamond interacts with light and how it complements the wearer’s hand are irreplaceable aspects of selecting the perfect cushion cut diamond.”
By being equipped with this knowledge and a trusted expert’s guidance, you can find a cushion cut diamond that not only meets your expectations in size and weight but also transcends them in beauty and brilliance. Whether for an engagement ring, a celebratory gift, or a personal investment, the cushion cut diamond remains a classic choice that carries a legacy of sophistication.
