How big is a 6 carat heart shaped diamond?

By HeyGema™ · Updated November 5, 2026

In short

A 6 carat heart shaped diamond measures about 11.8 x 11.8 mm. It faces up 17% smaller than a round diamond of the same weight. On a size 6 finger it covers 72% of the width. For the same weight, a round diamond is 11.7 mm.

11.8 x 11.8 mm6 carat heart
0.47 x 0.47 inthe same in inches
-17%face-up size vs a round
72%of a size 6 finger's width

Carat to mm calculator

ShapeGemCarat

About 11.8 x 11.8 mm

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

6 ct heart

11.8 x 11.8 mm

6 ct round

11.7 mm

Side by side

6 ct round inside 6 ct heart

A 6 carat heart diamond beside a 6 carat round, to the same scale.

6 carat heart diamond size

A well-cut 6 carat heart shaped diamond measures about 11.8 x 11.8 mm (0.47 x 0.47 inches) at a length-to-width ratio of 1.00:1. It faces up 17% smaller than a round diamond of the same weight. It weighs 1.20 grams.

6 carat heart on a finger

11.8 mm stone on a 16.5 mm finger: it covers 72% of the widthA 6 carat heart diamond on a size 6 finger.

4: Finger width: 14.9 mm; Heart covers: 79%

5: Finger width: 15.7 mm; Heart covers: 75%

6: Finger width: 16.5 mm; Heart covers: 72%

7: Finger width: 17.3 mm; Heart covers: 68%

8: Finger width: 18.1 mm; Heart covers: 65%

9: Finger width: 18.9 mm; Heart covers: 62%

US ring size	Finger width	Heart covers
4	14.9 mm	79%
5	15.7 mm	75%
6	16.5 mm	72%
7	17.3 mm	68%
8	18.1 mm	65%
9	18.9 mm	62%

Heart sizes near 6 carat

4 carat: Length x width: 10.3 x 10.3 mm; Round of the same weight: 10.2 mm

5 carat: Length x width: 11.1 x 11.1 mm; Round of the same weight: 11.0 mm

6 (this page): Length x width: 11.8 x 11.8 mm; Round of the same weight: 11.7 mm

8 carat: Length x width: 13.0 x 13.0 mm; Round of the same weight: 12.9 mm

10 carat: Length x width: 14.0 x 14.0 mm; Round of the same weight: 13.9 mm

Carat	Length x width	Round of the same weight
4 carat	10.3 x 10.3 mm	10.2 mm
5 carat	11.1 x 11.1 mm	11.0 mm
6 (this page)	11.8 x 11.8 mm	11.7 mm
8 carat	13.0 x 13.0 mm	12.9 mm
10 carat	14.0 x 14.0 mm	13.9 mm

6 carat in other shapes

Every row is a well-cut diamond of 6 carat. The last column is the face-up size against the heart.

Round: Length x width: 11.7 mm; Against heart: +21%

Oval: Length x width: 14.5 x 10.0 mm; Against heart: +28%

Cushion: Length x width: 10.2 x 10.2 mm; Against heart: +4%

Princess: Length x width: 10.0 x 10.0 mm; Against heart: +11%

Emerald cut: Length x width: 12.7 x 9.1 mm; Against heart: +25%

Asscher: Length x width: 10.0 x 10.0 mm; Against heart: +2%

Radiant: Length x width: 11.8 x 9.1 mm; Against heart: +18%

Pear: Length x width: 15.4 x 10.0 mm; Against heart: +17%

Marquise: Length x width: 18.9 x 9.4 mm; Against heart: +40%

Trillion: Length x width: 12.7 x 12.7 mm; Against heart: +4%

Baguette: Length x width: 14.5 x 7.3 mm; Against heart: +18%

Shape	Length x width	Against heart
Round	11.7 mm	+21%
Oval	14.5 x 10.0 mm	+28%
Cushion	10.2 x 10.2 mm	+4%
Princess	10.0 x 10.0 mm	+11%
Emerald cut	12.7 x 9.1 mm	+25%
Asscher	10.0 x 10.0 mm	+2%
Radiant	11.8 x 9.1 mm	+18%
Pear	15.4 x 10.0 mm	+17%
Marquise	18.9 x 9.4 mm	+40%
Trillion	12.7 x 12.7 mm	+4%
Baguette	14.5 x 7.3 mm	+18%

Questions

A 6 carat heart shaped diamond is about 11.8 x 11.8 mm at the usual 1.00:1 ratio.

No. Face-up, a 6 carat heart is 17% smaller than a 6 carat round (11.7 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.