How big is a 4 carat round diamond?
By HeyGema™ · Updated
In short
A 4 carat round diamond measures about 10.2 mm. On a size 6 finger it covers 62% of the width. For the same weight, a round diamond is 10.2 mm.
- 10.2 mm4 carat round
- 0.40 inthe same in inches
- referenceface-up size vs a round
- 62%of a size 6 finger's width
Carat to mm calculator
About 10.2 x 10.2 mm
An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.
4 ct round
10.2 mm
4 ct round
10.2 mm
Side by side
4 ct round inside 4 ct round
4 carat round diamond size
A well-cut 4 carat round diamond measures about 10.2 mm (0.40 inches) at a length-to-width ratio of 1.00:1. It weighs 0.80 grams.
4 carat round on a finger
- 4
- Finger width: 14.9 mm
- Round covers: 69%
- 5
- Finger width: 15.7 mm
- Round covers: 65%
- 6
- Finger width: 16.5 mm
- Round covers: 62%
- 7
- Finger width: 17.3 mm
- Round covers: 59%
- 8
- Finger width: 18.1 mm
- Round covers: 56%
- 9
- Finger width: 18.9 mm
- Round covers: 54%
Round sizes near 4 carat
- 3 carat
- Length x width: 9.3 mm
- Round of the same weight: 9.3 mm
- 3.5 carat
- Length x width: 9.8 mm
- Round of the same weight: 9.8 mm
- 4 (this page)
- Length x width: 10.2 mm
- Round of the same weight: 10.2 mm
- 5 carat
- Length x width: 11.0 mm
- Round of the same weight: 11.0 mm
- 6 carat
- Length x width: 11.7 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 round.
- Oval
- Length x width: 12.7 x 8.7 mm
- Against round: +6%
- Cushion
- Length x width: 8.9 x 8.9 mm
- Against round: -14%
- Princess
- Length x width: 8.7 x 8.7 mm
- Against round: -8%
- Emerald cut
- Length x width: 11.1 x 7.9 mm
- Against round: +4%
- Asscher
- Length x width: 8.7 x 8.7 mm
- Against round: -16%
- Radiant
- Length x width: 10.3 x 7.9 mm
- Against round: -2%
- Pear
- Length x width: 13.5 x 8.7 mm
- Against round: -3%
- Marquise
- Length x width: 16.5 x 8.3 mm
- Against round: +16%
- Heart
- Length x width: 10.3 x 10.3 mm
- Against round: -17%
- Trillion
- Length x width: 11.1 x 11.1 mm
- Against round: -14%
- Baguette
- Length x width: 12.7 x 6.3 mm
- Against round: -2%
Questions
A 4 carat round diamond is about 10.2 mm at the usual 1.00:1 ratio.
A 4 carat round diamond is about 0.40 inches across.
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.