Cushion cut diamond size chart: carat to mm
By HeyGema™ · Updated
In short
A 1 carat cushion cut diamond measures about 5.6 x 5.6 mm face-up. It faces up 14% smaller than a 1 carat round diamond.
Carat to mm calculator
About 5.6 x 5.6 mm
An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.
Cushion cut diamond size chart (carat to mm)
Face-up length and width of a well-cut cushion cut diamond at a length-to-width ratio of 1.00:1.
- 0.25
- Size: 3.5 x 3.5 mm
- 0.33
- Size: 3.9 x 3.9 mm
- 0.5
- Size: 4.4 x 4.4 mm
- 0.75
- Size: 5.1 x 5.1 mm
- 1
- Size: 5.6 x 5.6 mm
- 1.25
- Size: 6.0 x 6.0 mm
- 1.5
- Size: 6.4 x 6.4 mm
- 2
- Size: 7.1 x 7.1 mm
- 2.5
- Size: 7.6 x 7.6 mm
- 3
- Size: 8.1 x 8.1 mm
- 4
- Size: 8.9 x 8.9 mm
- 5
- Size: 9.6 x 9.6 mm
Size by length-to-width ratio
The same weight can be long and thin or short and wide. These are 1 carat sizes at each ratio.
- 1.00:1
- 1 ct: 5.6 x 5.6 mm
- 1.10:1
- 1 ct: 5.9 x 5.3 mm
- 1.20:1
- 1 ct: 6.1 x 5.1 mm
- 1.30:1
- 1 ct: 6.4 x 4.9 mm
Cushion cut diamond on a finger
How much of the finger's width a 1 carat cushion cut diamond covers, by US ring size. Finger width is taken as the ring's inside diameter. The more of the finger it covers, the bigger it looks.
- 4
- Finger width: 14.9 mm
- Stone covers: 38%
- 5
- Finger width: 15.7 mm
- Stone covers: 36%
- 6
- Finger width: 16.5 mm
- Stone covers: 34%
- 7
- Finger width: 17.3 mm
- Stone covers: 32%
- 8
- Finger width: 18.1 mm
- Stone covers: 31%
Check the real size
A chart on a screen is hard to picture. Hold a ruler or a bank card (85.6 x 54 mm) up to the screen, or ask your jeweler for a cubic zirconia of the same size to try on.