How big is a 3 carat round diamond?
By HeyGema™ · Updated
In short
A 3 carat round diamond measures about 9.3 mm. On a size 6 finger it covers 56% of the width. For the same weight, a round diamond is 9.3 mm.
- 9.3 mm3 carat round
- 0.37 inthe same in inches
- referenceface-up size vs a round
- 56%of a size 6 finger's width
Carat to mm calculator
About 9.3 x 9.3 mm
An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.
3 ct round
9.3 mm
3 ct round
9.3 mm
Side by side
3 ct round inside 3 ct round
3 carat round diamond size
A well-cut 3 carat round diamond measures about 9.3 mm (0.37 inches) at a length-to-width ratio of 1.00:1. It weighs 0.60 grams.
3 carat round on a finger
- 4
- Finger width: 14.9 mm
- Round covers: 63%
- 5
- Finger width: 15.7 mm
- Round covers: 59%
- 6
- Finger width: 16.5 mm
- Round covers: 56%
- 7
- Finger width: 17.3 mm
- Round covers: 54%
- 8
- Finger width: 18.1 mm
- Round covers: 51%
- 9
- Finger width: 18.9 mm
- Round covers: 49%
Round sizes near 3 carat
- 2.25 carat
- Length x width: 8.5 mm
- Round of the same weight: 8.5 mm
- 2.5 carat
- Length x width: 8.8 mm
- Round of the same weight: 8.8 mm
- 3 (this page)
- 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 carat
- Length x width: 10.2 mm
- Round of the same weight: 10.2 mm
3 carat in other shapes
Every row is a well-cut diamond of 3 carat. The last column is the face-up size against the round.
- Oval
- Length x width: 11.5 x 7.9 mm
- Against round: +6%
- Cushion
- Length x width: 8.1 x 8.1 mm
- Against round: -14%
- Princess
- Length x width: 7.9 x 7.9 mm
- Against round: -8%
- Emerald cut
- Length x width: 10.1 x 7.2 mm
- Against round: +4%
- Asscher
- Length x width: 7.9 x 7.9 mm
- Against round: -16%
- Radiant
- Length x width: 9.4 x 7.2 mm
- Against round: -2%
- Pear
- Length x width: 12.3 x 7.9 mm
- Against round: -3%
- Marquise
- Length x width: 15.0 x 7.5 mm
- Against round: +16%
- Heart
- Length x width: 9.4 x 9.4 mm
- Against round: -17%
- Trillion
- Length x width: 10.1 x 10.1 mm
- Against round: -14%
- Baguette
- Length x width: 11.5 x 5.8 mm
- Against round: -2%
Questions
A 3 carat round diamond is about 9.3 mm at the usual 1.00:1 ratio.
A 3 carat round diamond is about 0.37 inches across.
There is no rule. The stone is 63% of the width of a size 4 finger and 51% 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.