How big is a 8 carat Asscher cut diamond?

By HeyGema™ · Updated November 5, 2026

In short

A 8 carat Asscher cut diamond measures about 11.0 x 11.0 mm. It faces up 16% smaller than a round diamond of the same weight. On a size 6 finger it covers 67% of the width. For the same weight, a round diamond is 12.9 mm.

11.0 x 11.0 mm8 carat asscher
0.43 x 0.43 inthe same in inches
-16%face-up size vs a round
67%of a size 6 finger's width

Carat to mm calculator

ShapeGemCarat

About 11.0 x 11.0 mm

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

8 ct asscher

11.0 x 11.0 mm

8 ct round

12.9 mm

Side by side

8 ct asscher inside 8 ct round

A 8 carat asscher diamond beside a 8 carat round, to the same scale.

8 carat asscher diamond size

A well-cut 8 carat Asscher cut diamond measures about 11.0 x 11.0 mm (0.43 x 0.43 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 1.60 grams.

8 carat asscher on a finger

11.0 mm stone on a 16.5 mm finger: it covers 67% of the widthA 8 carat asscher diamond on a size 6 finger.

4: Finger width: 14.9 mm; Asscher covers: 74%

5: Finger width: 15.7 mm; Asscher covers: 70%

6: Finger width: 16.5 mm; Asscher covers: 67%

7: Finger width: 17.3 mm; Asscher covers: 64%

8: Finger width: 18.1 mm; Asscher covers: 61%

9: Finger width: 18.9 mm; Asscher covers: 58%

US ring size	Finger width	Asscher covers
4	14.9 mm	74%
5	15.7 mm	70%
6	16.5 mm	67%
7	17.3 mm	64%
8	18.1 mm	61%
9	18.9 mm	58%

Asscher sizes near 8 carat

5 carat: Length x width: 9.4 x 9.4 mm; Round of the same weight: 11.0 mm

6 carat: Length x width: 10.0 x 10.0 mm; Round of the same weight: 11.7 mm

8 (this page): Length x width: 11.0 x 11.0 mm; Round of the same weight: 12.9 mm

10 carat: Length x width: 11.8 x 11.8 mm; Round of the same weight: 13.9 mm

Carat	Length x width	Round of the same weight
5 carat	9.4 x 9.4 mm	11.0 mm
6 carat	10.0 x 10.0 mm	11.7 mm
8 (this page)	11.0 x 11.0 mm	12.9 mm
10 carat	11.8 x 11.8 mm	13.9 mm

8 carat in other shapes

Every row is a well-cut diamond of 8 carat. The last column is the face-up size against the asscher.

Round: Length x width: 12.9 mm; Against asscher: +18%

Oval: Length x width: 16.0 x 11.0 mm; Against asscher: +25%

Cushion: Length x width: 11.2 x 11.2 mm; Against asscher: +2%

Princess: Length x width: 11.0 x 11.0 mm; Against asscher: +9%

Emerald cut: Length x width: 14.0 x 10.0 mm; Against asscher: +23%

Radiant: Length x width: 13.0 x 10.0 mm; Against asscher: +16%

Pear: Length x width: 17.0 x 11.0 mm; Against asscher: +15%

Marquise: Length x width: 20.8 x 10.4 mm; Against asscher: +37%

Heart: Length x width: 13.0 x 13.0 mm; Against asscher: -2%

Trillion: Length x width: 14.0 x 14.0 mm; Against asscher: +2%

Baguette: Length x width: 16.0 x 8.0 mm; Against asscher: +16%

Shape	Length x width	Against asscher
Round	12.9 mm	+18%
Oval	16.0 x 11.0 mm	+25%
Cushion	11.2 x 11.2 mm	+2%
Princess	11.0 x 11.0 mm	+9%
Emerald cut	14.0 x 10.0 mm	+23%
Radiant	13.0 x 10.0 mm	+16%
Pear	17.0 x 11.0 mm	+15%
Marquise	20.8 x 10.4 mm	+37%
Heart	13.0 x 13.0 mm	-2%
Trillion	14.0 x 14.0 mm	+2%
Baguette	16.0 x 8.0 mm	+16%

Questions

A 8 carat Asscher cut diamond is about 11.0 x 11.0 mm at the usual 1.00:1 ratio.

No. Face-up, a 8 carat asscher is 16% smaller than a 8 carat round (12.9 mm).

There is no rule. The stone is wider than most fingers. 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.