How big is a 0.75 carat trillion cut diamond?

By HeyGema™ · Updated November 5, 2026

In short

A 0.75 carat trillion cut diamond measures about 6.4 x 6.4 mm. It faces up 14% smaller than a round diamond of the same weight. On a size 6 finger it covers 39% of the width. For the same weight, a round diamond is 5.9 mm.

6.4 x 6.4 mm0.75 carat trillion
0.25 x 0.25 inthe same in inches
-14%face-up size vs a round
39%of a size 6 finger's width

Carat to mm calculator

ShapeGemCarat

About 6.4 x 6.4 mm

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

0.75 ct trillion

6.4 x 6.4 mm

0.75 ct round

5.9 mm

Side by side

0.75 ct round inside 0.75 ct trillion

A 0.75 carat trillion diamond beside a 0.75 carat round, to the same scale.

0.75 carat trillion diamond size

A well-cut 0.75 carat trillion cut diamond measures about 6.4 x 6.4 mm (0.25 x 0.25 inches) at a length-to-width ratio of 1.00:1. It faces up 14% smaller than a round diamond of the same weight. It weighs 0.15 grams.

0.75 carat trillion on a finger

6.4 mm stone on a 16.5 mm finger: it covers 39% of the widthA 0.75 carat trillion diamond on a size 6 finger.

4: Finger width: 14.9 mm; Trillion covers: 43%

5: Finger width: 15.7 mm; Trillion covers: 41%

6: Finger width: 16.5 mm; Trillion covers: 39%

7: Finger width: 17.3 mm; Trillion covers: 37%

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

9: Finger width: 18.9 mm; Trillion covers: 34%

US ring size	Finger width	Trillion covers
4	14.9 mm	43%
5	15.7 mm	41%
6	16.5 mm	39%
7	17.3 mm	37%
8	18.1 mm	35%
9	18.9 mm	34%

Trillion sizes near 0.75 carat

0.33 carat: Length x width: 4.8 x 4.8 mm; Round of the same weight: 4.5 mm

0.5 carat: Length x width: 5.6 x 5.6 mm; Round of the same weight: 5.1 mm

0.75 (this page): Length x width: 6.4 x 6.4 mm; Round of the same weight: 5.9 mm

1 carat: Length x width: 7.0 x 7.0 mm; Round of the same weight: 6.5 mm

1.25 carat: Length x width: 7.5 x 7.5 mm; Round of the same weight: 6.9 mm

Carat	Length x width	Round of the same weight
0.33 carat	4.8 x 4.8 mm	4.5 mm
0.5 carat	5.6 x 5.6 mm	5.1 mm
0.75 (this page)	6.4 x 6.4 mm	5.9 mm
1 carat	7.0 x 7.0 mm	6.5 mm
1.25 carat	7.5 x 7.5 mm	6.9 mm

0.75 carat in other shapes

Every row is a well-cut diamond of 0.75 carat. The last column is the face-up size against the trillion.

Round: Length x width: 5.9 mm; Against trillion: +16%

Oval: Length x width: 7.3 x 5.0 mm; Against trillion: +22%

Cushion: Length x width: 5.1 x 5.1 mm; Against trillion: -1%

Princess: Length x width: 5.0 x 5.0 mm; Against trillion: +6%

Emerald cut: Length x width: 6.4 x 4.5 mm; Against trillion: +20%

Asscher: Length x width: 5.0 x 5.0 mm; Against trillion: -2%

Radiant: Length x width: 5.9 x 4.5 mm; Against trillion: +13%

Pear: Length x width: 7.7 x 5.0 mm; Against trillion: +12%

Marquise: Length x width: 9.4 x 4.7 mm; Against trillion: +34%

Heart: Length x width: 5.9 x 5.9 mm; Against trillion: -4%

Baguette: Length x width: 7.3 x 3.6 mm; Against trillion: +13%

Shape	Length x width	Against trillion
Round	5.9 mm	+16%
Oval	7.3 x 5.0 mm	+22%
Cushion	5.1 x 5.1 mm	-1%
Princess	5.0 x 5.0 mm	+6%
Emerald cut	6.4 x 4.5 mm	+20%
Asscher	5.0 x 5.0 mm	-2%
Radiant	5.9 x 4.5 mm	+13%
Pear	7.7 x 5.0 mm	+12%
Marquise	9.4 x 4.7 mm	+34%
Heart	5.9 x 5.9 mm	-4%
Baguette	7.3 x 3.6 mm	+13%

Questions

A 0.75 carat trillion cut diamond is about 6.4 x 6.4 mm at the usual 1.00:1 ratio.

No. Face-up, a 0.75 carat trillion is 14% smaller than a 0.75 carat round (5.9 mm).

There is no rule. The stone is 43% 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.