How big is a 4 carat trillion cut diamond?

By HeyGema™ · Updated

In short

A 4 carat trillion cut diamond measures about 11.1 x 11.1 mm. It faces up 14% smaller than a round diamond of the same weight. On a size 6 finger it covers 67% of the width. For the same weight, a round diamond is 10.2 mm.

Carat to mm calculator

About 11.1 x 11.1 mm

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

4 ct trillion
11.1 x 11.1 mm
4 ct round
10.2 mm
Side by side
4 ct round inside 4 ct trillion
A 4 carat trillion diamond beside a 4 carat round, to the same scale.

4 carat trillion diamond size

A well-cut 4 carat trillion cut diamond measures about 11.1 x 11.1 mm (0.44 x 0.44 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 0.80 grams.

4 carat trillion on a finger

11.1 mm
11.1 mm stone on a 16.5 mm finger: it covers 67% of the widthA 4 carat trillion diamond on a size 6 finger.
4
Finger width: 14.9 mm
Trillion covers: 75%
5
Finger width: 15.7 mm
Trillion covers: 71%
6
Finger width: 16.5 mm
Trillion covers: 67%
7
Finger width: 17.3 mm
Trillion covers: 64%
8
Finger width: 18.1 mm
Trillion covers: 61%
9
Finger width: 18.9 mm
Trillion covers: 59%

Trillion sizes near 4 carat

3 carat
Length x width: 10.1 x 10.1 mm
Round of the same weight: 9.3 mm
3.5 carat
Length x width: 10.6 x 10.6 mm
Round of the same weight: 9.8 mm
4 (this page)
Length x width: 11.1 x 11.1 mm
Round of the same weight: 10.2 mm
5 carat
Length x width: 12.0 x 12.0 mm
Round of the same weight: 11.0 mm
6 carat
Length x width: 12.7 x 12.7 mm
Round of the same weight: 11.7 mm

4 carat in other shapes

Every row is a well-cut diamond of 4 carat. The last column is the face-up size against the trillion.

Round
Length x width: 10.2 mm
Against trillion: +16%
Oval
Length x width: 12.7 x 8.7 mm
Against trillion: +22%
Cushion
Length x width: 8.9 x 8.9 mm
Against trillion: -1%
Princess
Length x width: 8.7 x 8.7 mm
Against trillion: +6%
Emerald cut
Length x width: 11.1 x 7.9 mm
Against trillion: +20%
Asscher
Length x width: 8.7 x 8.7 mm
Against trillion: -2%
Radiant
Length x width: 10.3 x 7.9 mm
Against trillion: +13%
Pear
Length x width: 13.5 x 8.7 mm
Against trillion: +12%
Marquise
Length x width: 16.5 x 8.3 mm
Against trillion: +34%
Heart
Length x width: 10.3 x 10.3 mm
Against trillion: -4%
Baguette
Length x width: 12.7 x 6.3 mm
Against trillion: +13%

Questions

A 4 carat trillion cut diamond is about 11.1 x 11.1 mm at the usual 1.00:1 ratio.
No. Face-up, a 4 carat trillion is 14% smaller than a 4 carat round (10.2 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.

More size charts