How big is a 1.25 carat cushion cut diamond?

By HeyGema™ · Updated

In short

A 1.25 carat cushion cut diamond measures about 6.0 x 6.0 mm. It faces up 14% smaller than a round diamond of the same weight. On a size 6 finger it covers 37% of the width. For the same weight, a round diamond is 6.9 mm.

Carat to mm calculator

About 6.0 x 6.0 mm

An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.

1.25 ct cushion
6.0 x 6.0 mm
1.25 ct round
6.9 mm
Side by side
1.25 ct cushion inside 1.25 ct round
A 1.25 carat cushion diamond beside a 1.25 carat round, to the same scale.

1.25 carat cushion diamond size

A well-cut 1.25 carat cushion cut diamond measures about 6.0 x 6.0 mm (0.24 x 0.24 inches) at a length-to-width ratio of 1.00:1. It faces up 14% smaller than a round diamond of the same weight. It weighs 0.25 grams.

1.25 carat cushion size by length-to-width ratio

The same weight can be long and narrow or short and wide. These are 1.25 carat sizes at each ratio. A longer ratio runs the stone along the finger and makes it look slimmer. The face-up area stays almost the same.

1.00:1
Length x width: 6.0 x 6.0 mm
Width on the finger: 37% of a size 6 finger
1.10:1
Length x width: 6.3 x 5.8 mm
Width on the finger: 35% of a size 6 finger
1.20:1
Length x width: 6.6 x 5.5 mm
Width on the finger: 33% of a size 6 finger
1.30:1
Length x width: 6.9 x 5.3 mm
Width on the finger: 32% of a size 6 finger

1.25 carat cushion on a finger

6.0 mm
6.0 mm stone on a 16.5 mm finger: it covers 37% of the widthA 1.25 carat cushion diamond on a size 6 finger.
4
Finger width: 14.9 mm
Cushion covers: 41%
5
Finger width: 15.7 mm
Cushion covers: 38%
6
Finger width: 16.5 mm
Cushion covers: 37%
7
Finger width: 17.3 mm
Cushion covers: 35%
8
Finger width: 18.1 mm
Cushion covers: 33%
9
Finger width: 18.9 mm
Cushion covers: 32%

Cushion sizes near 1.25 carat

0.75 carat
Length x width: 5.1 x 5.1 mm
Round of the same weight: 5.9 mm
1 carat
Length x width: 5.6 x 5.6 mm
Round of the same weight: 6.5 mm
1.25 (this page)
Length x width: 6.0 x 6.0 mm
Round of the same weight: 6.9 mm
1.5 carat
Length x width: 6.4 x 6.4 mm
Round of the same weight: 7.4 mm
1.75 carat
Length x width: 6.7 x 6.7 mm
Round of the same weight: 7.8 mm

1.25 carat in other shapes

Every row is a well-cut diamond of 1.25 carat. The last column is the face-up size against the cushion.

Round
Length x width: 6.9 mm
Against cushion: +16%
Oval
Length x width: 8.6 x 5.9 mm
Against cushion: +23%
Princess
Length x width: 5.9 x 5.9 mm
Against cushion: +7%
Emerald cut
Length x width: 7.5 x 5.4 mm
Against cushion: +21%
Asscher
Length x width: 5.9 x 5.9 mm
Against cushion: -2%
Radiant
Length x width: 7.0 x 5.4 mm
Against cushion: +14%
Pear
Length x width: 9.2 x 5.9 mm
Against cushion: +13%
Marquise
Length x width: 11.2 x 5.6 mm
Against cushion: +35%
Heart
Length x width: 7.0 x 7.0 mm
Against cushion: -4%
Trillion
Length x width: 7.5 x 7.5 mm
Against cushion: +1%
Baguette
Length x width: 8.6 x 4.3 mm
Against cushion: +14%

Questions

A 1.25 carat cushion cut diamond is about 6.0 x 6.0 mm at the usual 1.00:1 ratio.
No. Face-up, a 1.25 carat cushion is 14% smaller than a 1.25 carat round (6.9 mm).
There is no rule. The stone is 41% of the width of a size 4 finger and 33% of a size 8. Compare it with a ring you have tried on in the finger chart above.
Yes. A lab grown diamond has the same density as a mined one, so it measures the same for the same weight.

More size charts