How big is a 1.5 carat Asscher cut diamond?

By HeyGema™ · Updated November 5, 2026

In short

A 1.5 carat Asscher cut diamond measures about 6.3 x 6.3 mm. It faces up 16% smaller than a round diamond of the same weight. On a size 6 finger it covers 38% of the width. For the same weight, a round diamond is 7.4 mm.

6.3 x 6.3 mm1.5 carat asscher
0.25 x 0.25 inthe same in inches
-16%face-up size vs a round
38%of a size 6 finger's width

Carat to mm calculator

ShapeGemCarat

About 6.3 x 6.3 mm

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

1.5 ct asscher

6.3 x 6.3 mm

1.5 ct round

7.4 mm

Side by side

1.5 ct asscher inside 1.5 ct round

A 1.5 carat asscher diamond beside a 1.5 carat round, to the same scale.

1.5 carat asscher diamond size

A well-cut 1.5 carat Asscher cut diamond measures about 6.3 x 6.3 mm (0.25 x 0.25 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 0.30 grams.

1.5 carat asscher on a finger

6.3 mm stone on a 16.5 mm finger: it covers 38% of the widthA 1.5 carat asscher diamond on a size 6 finger.

4: Finger width: 14.9 mm; Asscher covers: 42%

5: Finger width: 15.7 mm; Asscher covers: 40%

6: Finger width: 16.5 mm; Asscher covers: 38%

7: Finger width: 17.3 mm; Asscher covers: 36%

8: Finger width: 18.1 mm; Asscher covers: 35%

9: Finger width: 18.9 mm; Asscher covers: 33%

US ring size	Finger width	Asscher covers
4	14.9 mm	42%
5	15.7 mm	40%
6	16.5 mm	38%
7	17.3 mm	36%
8	18.1 mm	35%
9	18.9 mm	33%

Asscher sizes near 1.5 carat

1 carat: 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 (this page): Length x width: 6.3 x 6.3 mm; Round of the same weight: 7.4 mm

1.75 carat: Length x width: 6.6 x 6.6 mm; Round of the same weight: 7.8 mm

2 carat: Length x width: 6.9 x 6.9 mm; Round of the same weight: 8.1 mm

Carat	Length x width	Round of the same weight
1 carat	5.5 x 5.5 mm	6.5 mm
1.25 carat	5.9 x 5.9 mm	6.9 mm
1.5 (this page)	6.3 x 6.3 mm	7.4 mm
1.75 carat	6.6 x 6.6 mm	7.8 mm
2 carat	6.9 x 6.9 mm	8.1 mm

1.5 carat in other shapes

Every row is a well-cut diamond of 1.5 carat. The last column is the face-up size against the asscher.

Round: Length x width: 7.4 mm; Against asscher: +18%

Oval: Length x width: 9.2 x 6.3 mm; Against asscher: +25%

Cushion: Length x width: 6.4 x 6.4 mm; Against asscher: +2%

Princess: Length x width: 6.3 x 6.3 mm; Against asscher: +9%

Emerald cut: Length x width: 8.0 x 5.7 mm; Against asscher: +23%

Radiant: Length x width: 7.4 x 5.7 mm; Against asscher: +16%

Pear: Length x width: 9.7 x 6.3 mm; Against asscher: +15%

Marquise: Length x width: 11.9 x 6.0 mm; Against asscher: +37%

Heart: Length x width: 7.4 x 7.4 mm; Against asscher: -2%

Trillion: Length x width: 8.0 x 8.0 mm; Against asscher: +2%

Baguette: Length x width: 9.2 x 4.6 mm; Against asscher: +16%

Shape	Length x width	Against asscher
Round	7.4 mm	+18%
Oval	9.2 x 6.3 mm	+25%
Cushion	6.4 x 6.4 mm	+2%
Princess	6.3 x 6.3 mm	+9%
Emerald cut	8.0 x 5.7 mm	+23%
Radiant	7.4 x 5.7 mm	+16%
Pear	9.7 x 6.3 mm	+15%
Marquise	11.9 x 6.0 mm	+37%
Heart	7.4 x 7.4 mm	-2%
Trillion	8.0 x 8.0 mm	+2%
Baguette	9.2 x 4.6 mm	+16%

Questions

A 1.5 carat Asscher cut diamond is about 6.3 x 6.3 mm at the usual 1.00:1 ratio.

No. Face-up, a 1.5 carat asscher is 16% smaller than a 1.5 carat round (7.4 mm).

There is no rule. The stone is 42% of the width of a size 4 finger and 35% 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.