How big is a 0.33 carat Asscher cut diamond?

By HeyGema™ · Updated November 5, 2026

In short

A 0.33 carat Asscher cut diamond measures about 3.8 x 3.8 mm. It faces up 16% smaller than a round diamond of the same weight. On a size 6 finger it covers 23% of the width. For the same weight, a round diamond is 4.5 mm.

3.8 x 3.8 mm0.33 carat asscher
0.15 x 0.15 inthe same in inches
-16%face-up size vs a round
23%of a size 6 finger's width

Carat to mm calculator

ShapeGemCarat

About 3.8 x 3.8 mm

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

0.33 ct asscher

3.8 x 3.8 mm

0.33 ct round

4.5 mm

Side by side

0.33 ct asscher inside 0.33 ct round

A 0.33 carat asscher diamond beside a 0.33 carat round, to the same scale.

0.33 carat asscher diamond size

A well-cut 0.33 carat Asscher cut diamond measures about 3.8 x 3.8 mm (0.15 x 0.15 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 0.066 grams.

0.33 carat asscher on a finger

3.8 mm stone on a 16.5 mm finger: it covers 23% of the widthA 0.33 carat asscher diamond on a size 6 finger.

4: Finger width: 14.9 mm; Asscher covers: 26%

5: Finger width: 15.7 mm; Asscher covers: 24%

6: Finger width: 16.5 mm; Asscher covers: 23%

7: Finger width: 17.3 mm; Asscher covers: 22%

8: Finger width: 18.1 mm; Asscher covers: 21%

9: Finger width: 18.9 mm; Asscher covers: 20%

US ring size	Finger width	Asscher covers
4	14.9 mm	26%
5	15.7 mm	24%
6	16.5 mm	23%
7	17.3 mm	22%
8	18.1 mm	21%
9	18.9 mm	20%

Asscher sizes near 0.33 carat

0.25 carat: Length x width: 3.5 x 3.5 mm; Round of the same weight: 4.1 mm

0.33 (this page): Length x width: 3.8 x 3.8 mm; Round of the same weight: 4.5 mm

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

Carat	Length x width	Round of the same weight
0.25 carat	3.5 x 3.5 mm	4.1 mm
0.33 (this page)	3.8 x 3.8 mm	4.5 mm
0.5 carat	4.4 x 4.4 mm	5.1 mm
0.75 carat	5.0 x 5.0 mm	5.9 mm

0.33 carat in other shapes

Every row is a well-cut diamond of 0.33 carat. The last column is the face-up size against the asscher.

Round: Length x width: 4.5 mm; Against asscher: +18%

Oval: Length x width: 5.5 x 3.8 mm; Against asscher: +25%

Cushion: Length x width: 3.9 x 3.9 mm; Against asscher: +2%

Princess: Length x width: 3.8 x 3.8 mm; Against asscher: +9%

Emerald cut: Length x width: 4.8 x 3.5 mm; Against asscher: +23%

Radiant: Length x width: 4.5 x 3.5 mm; Against asscher: +16%

Pear: Length x width: 5.9 x 3.8 mm; Against asscher: +15%

Marquise: Length x width: 7.2 x 3.6 mm; Against asscher: +37%

Heart: Length x width: 4.5 x 4.5 mm; Against asscher: -2%

Trillion: Length x width: 4.8 x 4.8 mm; Against asscher: +2%

Baguette: Length x width: 5.5 x 2.76 mm; Against asscher: +16%

Shape	Length x width	Against asscher
Round	4.5 mm	+18%
Oval	5.5 x 3.8 mm	+25%
Cushion	3.9 x 3.9 mm	+2%
Princess	3.8 x 3.8 mm	+9%
Emerald cut	4.8 x 3.5 mm	+23%
Radiant	4.5 x 3.5 mm	+16%
Pear	5.9 x 3.8 mm	+15%
Marquise	7.2 x 3.6 mm	+37%
Heart	4.5 x 4.5 mm	-2%
Trillion	4.8 x 4.8 mm	+2%
Baguette	5.5 x 2.76 mm	+16%

Questions

A 0.33 carat Asscher cut diamond is about 3.8 x 3.8 mm at the usual 1.00:1 ratio.

No. Face-up, a 0.33 carat asscher is 16% smaller than a 0.33 carat round (4.5 mm).

There is no rule. The stone is 26% of the width of a size 4 finger and 21% 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.