How big is a 1 carat Asscher cut diamond?

By HeyGema™ · Updated

In short

A 1 carat Asscher cut diamond measures about 5.5 x 5.5 mm. It faces up 16% smaller than a round diamond of the same weight. On a size 6 finger it covers 33% of the width. For the same weight, a round diamond is 6.5 mm.

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.

1 ct asscher
5.5 x 5.5 mm
1 ct round
6.5 mm
Side by side
1 ct asscher inside 1 ct round
A 1 carat asscher diamond beside a 1 carat round, to the same scale.

1 carat asscher diamond size

A well-cut 1 carat Asscher cut diamond measures about 5.5 x 5.5 mm (0.22 x 0.22 inches) at a length-to-width ratio of 1.00:1. It faces up 16% smaller than a round diamond of the same weight. It weighs 0.20 grams.

1 carat asscher on a finger

5.5 mm
5.5 mm stone on a 16.5 mm finger: it covers 33% of the widthA 1 carat asscher diamond on a size 6 finger.
4
Finger width: 14.9 mm
Asscher covers: 37%
5
Finger width: 15.7 mm
Asscher covers: 35%
6
Finger width: 16.5 mm
Asscher covers: 33%
7
Finger width: 17.3 mm
Asscher covers: 32%
8
Finger width: 18.1 mm
Asscher covers: 30%
9
Finger width: 18.9 mm
Asscher covers: 29%

Asscher sizes near 1 carat

0.5 carat
Length x width: 4.4 x 4.4 mm
Round of the same weight: 5.1 mm
0.75 carat
Length x width: 5.0 x 5.0 mm
Round of the same weight: 5.9 mm
1 (this page)
Length x width: 5.5 x 5.5 mm
Round of the same weight: 6.5 mm
1.25 carat
Length x width: 5.9 x 5.9 mm
Round of the same weight: 6.9 mm
1.5 carat
Length x width: 6.3 x 6.3 mm
Round of the same weight: 7.4 mm

1 carat in other shapes

Every row is a well-cut diamond of 1 carat. The last column is the face-up size against the asscher.

Round
Length x width: 6.5 mm
Against asscher: +18%
Oval
Length x width: 8.0 x 5.5 mm
Against asscher: +25%
Cushion
Length x width: 5.6 x 5.6 mm
Against asscher: +2%
Princess
Length x width: 5.5 x 5.5 mm
Against asscher: +9%
Emerald cut
Length x width: 7.0 x 5.0 mm
Against asscher: +23%
Radiant
Length x width: 6.5 x 5.0 mm
Against asscher: +16%
Pear
Length x width: 8.5 x 5.5 mm
Against asscher: +15%
Marquise
Length x width: 10.4 x 5.2 mm
Against asscher: +37%
Heart
Length x width: 6.5 x 6.5 mm
Against asscher: -2%
Trillion
Length x width: 7.0 x 7.0 mm
Against asscher: +2%
Baguette
Length x width: 8.0 x 4.0 mm
Against asscher: +16%

Questions

A 1 carat Asscher cut diamond is about 5.5 x 5.5 mm at the usual 1.00:1 ratio.
No. Face-up, a 1 carat asscher is 16% smaller than a 1 carat round (6.5 mm).
There is no rule. The stone is 37% of the width of a size 4 finger and 30% 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