How big is a 75 carat diamond?

By HeyGema™ · Updated

In short

A 75 carat round diamond measures about 27.2 mm across (1.07 inches) and weighs 15.00 grams. An oval of the same weight is 33.7 x 23.2 mm and an emerald cut 29.5 x 21.1 mm. On a size 6 finger a round 75 carat covers 165% of the width.

Carat to mm calculator

About 27.2 x 27.2 mm

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

Round
27.2 mm
Oval
33.7 x 23.2 mm
Cushion
23.6 x 23.6 mm
Princess
23.2 x 23.2 mm
Emerald cut
29.5 x 21.1 mm
Asscher
23.2 x 23.2 mm
Radiant
27.4 x 21.1 mm
Pear
35.8 x 23.2 mm
Marquise
43.9 x 21.9 mm
Heart
27.4 x 27.4 mm
Trillion
29.5 x 29.5 mm
Baguette
33.7 x 16.9 mm
= 10 mm in every picture above
A 75 carat diamond in 12 shapes, drawn to one scale from the chart below.

75 carat diamond size by shape

These are the face-up measurements of a well-cut 75 carat diamond. Weight is the same in every row, but the face-up size is not: the last column compares each cut with a round diamond of the same weight.

Round
Length x width: 27.2 mm
In inches: 1.07 in
Face-up size vs round: -
Oval
Length x width: 33.7 x 23.2 mm
In inches: 1.33 x 0.91 in
Face-up size vs round: +6%
Cushion
Length x width: 23.6 x 23.6 mm
In inches: 0.93 x 0.93 in
Face-up size vs round: -14%
Princess
Length x width: 23.2 x 23.2 mm
In inches: 0.91 x 0.91 in
Face-up size vs round: -8%
Emerald cut
Length x width: 29.5 x 21.1 mm
In inches: 1.16 x 0.83 in
Face-up size vs round: +4%
Asscher
Length x width: 23.2 x 23.2 mm
In inches: 0.91 x 0.91 in
Face-up size vs round: -16%
Radiant
Length x width: 27.4 x 21.1 mm
In inches: 1.08 x 0.83 in
Face-up size vs round: -2%
Pear
Length x width: 35.8 x 23.2 mm
In inches: 1.41 x 0.91 in
Face-up size vs round: -3%
Marquise
Length x width: 43.9 x 21.9 mm
In inches: 1.73 x 0.86 in
Face-up size vs round: +16%
Heart
Length x width: 27.4 x 27.4 mm
In inches: 1.08 x 1.08 in
Face-up size vs round: -17%
Trillion
Length x width: 29.5 x 29.5 mm
In inches: 1.16 x 1.16 in
Face-up size vs round: -14%
Baguette
Length x width: 33.7 x 16.9 mm
In inches: 1.33 x 0.66 in
Face-up size vs round: -2%

75 carat diamond next to a coin

75 ct diamond
27.2 mm
US nickel
21.2 mm
US quarter
24.3 mm
US half dollar
30.6 mm
A round 75 carat diamond is 27.2 mm wide, 89% of the width of a US half dollar (30.61 mm).

Is a 75 carat diamond big?

It depends on the hand. A round 75 carat covers 183% of the width of a size 4 finger, 165% of a size 6 and 150% of a size 8. At 75 carats a round diamond is 27.2 mm across, 89% of the width of a US half dollar (30.61 mm). A stone this size is usually worn as a pendant or made into a piece for it, not set in a ring.

27.2 mm
27.2 mm stone on a 16.5 mm finger: it covers 165% of the widthA round 75 carat diamond on a size 6 finger.

75 carat diamond on a finger, by ring size

The share of the finger's width that the stone covers, for the four most searched shapes. Elongated stones sit along the finger, so their width is what you see across it. Try other ring sizes in the diamond size on finger tool.

4
Finger width: 14.9 mm
Round: 183%
Oval: 156%
Cushion: 159%
Emerald cut: 142%
5
Finger width: 15.7 mm
Round: 173%
Oval: 148%
Cushion: 150%
Emerald cut: 134%
6
Finger width: 16.5 mm
Round: 165%
Oval: 141%
Cushion: 143%
Emerald cut: 128%
7
Finger width: 17.3 mm
Round: 157%
Oval: 134%
Cushion: 136%
Emerald cut: 122%
8
Finger width: 18.1 mm
Round: 150%
Oval: 128%
Cushion: 130%
Emerald cut: 116%
9
Finger width: 18.9 mm
Round: 144%
Oval: 122%
Cushion: 125%
Emerald cut: 111%

75 carat compared with nearby sizes

Round diamond diameter for the weights on either side of 75 carat. The last column is the difference in width from a 75 carat stone.

40 carat
Round diameter: 22.1 mm
Difference from 75 ct: -5.14 mm
50 carat
Round diameter: 23.8 mm
Difference from 75 ct: -3.44 mm
75 (this page)
Round diameter: 27.2 mm
Difference from 75 ct: -
100 carat
Round diameter: 29.9 mm
Difference from 75 ct: +2.74 mm

Other gems at 75 carat

Gems are not all as dense as diamond, so the same weight faces up bigger or smaller. Round stones of 75 carat:

Diamond
Round diameter: 27.2 mm
Against diamond: -
Moissanite
Round diameter: 28.0 mm
Against diamond: +3% wider
Sapphire
Round diameter: 26.1 mm
Against diamond: -4% wider
Ruby
Round diameter: 26.1 mm
Against diamond: -4% wider
Emerald
Round diameter: 29.6 mm
Against diamond: +9% wider
Aquamarine
Round diameter: 29.7 mm
Against diamond: +9% wider
Morganite
Round diameter: 29.4 mm
Against diamond: +8% wider
Tanzanite
Round diameter: 27.7 mm
Against diamond: +2% wider
Topaz
Round diameter: 27.2 mm
Against diamond: same
Amethyst
Round diameter: 29.9 mm
Against diamond: +10% wider
Spinel
Round diameter: 27.0 mm
Against diamond: -1% wider

How these sizes are worked out

We start from the face-up size of a well-cut 1 carat diamond of each shape and scale it with the cube root of the weight and the gem's density. They are estimates for a typical cut. See the methodology for the formulas, or use the calculator above for any weight.

Questions

A 75 carat round diamond is about 27.2 mm across. An oval of the same weight is 33.7 x 23.2 mm, a cushion cut 23.6 x 23.6 mm, a princess cut 23.2 x 23.2 mm and an emerald cut 29.5 x 21.1 mm.
A round 75 carat diamond is about 1.07 inches across.
75 carat is 15.00 grams. One carat is 200 milligrams (0.2 grams).
A round 75 carat covers 165% of the width of a size 6 finger. At 75 carats a round diamond is 27.2 mm across, 89% of the width of a US half dollar (30.61 mm). A stone this size is usually worn as a pendant or made into a piece for it, not set in a ring.
Marquise has the largest face-up area for 75 carat in our chart, +16% against a round. Heart has the smallest, -17%. See the shapes that look biggest.
Yes. A lab grown diamond is chemically the same as a mined one, with the same density, so 75 carat measures the same in mm. See the lab grown diamond size chart.

More size charts