How big is a 1 carat trillion cut diamond?

By HeyGema™ · Updated

In short

A 1 carat trillion cut diamond measures about 7.0 x 7.0 mm. It faces up 14% smaller than a round diamond of the same weight. On a size 6 finger it covers 42% of the width. For the same weight, a round diamond is 6.5 mm.

Carat to mm calculator

About 7.0 x 7.0 mm

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

1 ct trillion
7.0 x 7.0 mm
1 ct round
6.5 mm
Side by side
1 ct round inside 1 ct trillion
A 1 carat trillion diamond beside a 1 carat round, to the same scale.

1 carat trillion diamond size

A well-cut 1 carat trillion cut diamond measures about 7.0 x 7.0 mm (0.28 x 0.28 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 0.20 grams.

1 carat trillion on a finger

7.0 mm
7.0 mm stone on a 16.5 mm finger: it covers 42% of the widthA 1 carat trillion diamond on a size 6 finger.
4
Finger width: 14.9 mm
Trillion covers: 47%
5
Finger width: 15.7 mm
Trillion covers: 45%
6
Finger width: 16.5 mm
Trillion covers: 42%
7
Finger width: 17.3 mm
Trillion covers: 40%
8
Finger width: 18.1 mm
Trillion covers: 39%
9
Finger width: 18.9 mm
Trillion covers: 37%

Trillion sizes near 1 carat

0.5 carat
Length x width: 5.6 x 5.6 mm
Round of the same weight: 5.1 mm
0.75 carat
Length x width: 6.4 x 6.4 mm
Round of the same weight: 5.9 mm
1 (this page)
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
1.5 carat
Length x width: 8.0 x 8.0 mm
Round of the same weight: 7.4 mm

1 carat in other shapes

Every row is a well-cut diamond of 1 carat. The last column is the face-up size against the trillion.

Round
Length x width: 6.5 mm
Against trillion: +16%
Oval
Length x width: 8.0 x 5.5 mm
Against trillion: +22%
Cushion
Length x width: 5.6 x 5.6 mm
Against trillion: -1%
Princess
Length x width: 5.5 x 5.5 mm
Against trillion: +6%
Emerald cut
Length x width: 7.0 x 5.0 mm
Against trillion: +20%
Asscher
Length x width: 5.5 x 5.5 mm
Against trillion: -2%
Radiant
Length x width: 6.5 x 5.0 mm
Against trillion: +13%
Pear
Length x width: 8.5 x 5.5 mm
Against trillion: +12%
Marquise
Length x width: 10.4 x 5.2 mm
Against trillion: +34%
Heart
Length x width: 6.5 x 6.5 mm
Against trillion: -4%
Baguette
Length x width: 8.0 x 4.0 mm
Against trillion: +13%

Questions

A 1 carat trillion cut diamond is about 7.0 x 7.0 mm at the usual 1.00:1 ratio.
No. Face-up, a 1 carat trillion is 14% smaller than a 1 carat round (6.5 mm).
There is no rule. The stone is 47% of the width of a size 4 finger and 39% 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.

More size charts