How big is a 4 carat marquise diamond?

By HeyGema™ · Updated

In short

A 4 carat marquise diamond measures about 16.5 x 8.3 mm. It faces up 16% bigger than a round diamond of the same weight. On a size 6 finger it covers 50% of the width. For the same weight, a round diamond is 10.2 mm.

Carat to mm calculator

About 16.5 x 8.3 mm

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

4 ct marquise
16.5 x 8.3 mm
4 ct round
10.2 mm
Side by side
4 ct round inside 4 ct marquise
A 4 carat marquise diamond beside a 4 carat round, to the same scale.

4 carat marquise diamond size

A well-cut 4 carat marquise diamond measures about 16.5 x 8.3 mm (0.65 x 0.32 inches) at a length-to-width ratio of 2.00:1. It faces up 16% bigger than a round diamond of the same weight. It weighs 0.80 grams.

4 carat marquise size by length-to-width ratio

The same weight can be long and narrow or short and wide. These are 4 carat sizes at each ratio. A longer ratio runs the stone along the finger and makes it look slimmer. The face-up area stays almost the same.

1.80:1
Length x width: 15.7 x 8.7 mm
Width on the finger: 53% of a size 6 finger
2.00:1
Length x width: 16.5 x 8.3 mm
Width on the finger: 50% of a size 6 finger
2.20:1
Length x width: 17.3 x 7.9 mm
Width on the finger: 48% of a size 6 finger

4 carat marquise on a finger

8.3 mm
8.3 mm stone on a 16.5 mm finger: it covers 50% of the widthA 4 carat marquise diamond on a size 6 finger.
4
Finger width: 14.9 mm
Marquise covers: 55%
5
Finger width: 15.7 mm
Marquise covers: 53%
6
Finger width: 16.5 mm
Marquise covers: 50%
7
Finger width: 17.3 mm
Marquise covers: 48%
8
Finger width: 18.1 mm
Marquise covers: 46%
9
Finger width: 18.9 mm
Marquise covers: 44%

Marquise sizes near 4 carat

3 carat
Length x width: 15.0 x 7.5 mm
Round of the same weight: 9.3 mm
3.5 carat
Length x width: 15.8 x 7.9 mm
Round of the same weight: 9.8 mm
4 (this page)
Length x width: 16.5 x 8.3 mm
Round of the same weight: 10.2 mm
5 carat
Length x width: 17.8 x 8.9 mm
Round of the same weight: 11.0 mm
6 carat
Length x width: 18.9 x 9.4 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 marquise.

Round
Length x width: 10.2 mm
Against marquise: -14%
Oval
Length x width: 12.7 x 8.7 mm
Against marquise: -9%
Cushion
Length x width: 8.9 x 8.9 mm
Against marquise: -26%
Princess
Length x width: 8.7 x 8.7 mm
Against marquise: -21%
Emerald cut
Length x width: 11.1 x 7.9 mm
Against marquise: -10%
Asscher
Length x width: 8.7 x 8.7 mm
Against marquise: -27%
Radiant
Length x width: 10.3 x 7.9 mm
Against marquise: -16%
Pear
Length x width: 13.5 x 8.7 mm
Against marquise: -16%
Heart
Length x width: 10.3 x 10.3 mm
Against marquise: -28%
Trillion
Length x width: 11.1 x 11.1 mm
Against marquise: -25%
Baguette
Length x width: 12.7 x 6.3 mm
Against marquise: -15%

Questions

A 4 carat marquise diamond is about 16.5 x 8.3 mm at the usual 2.00:1 ratio.
Yes. Face-up, a 4 carat marquise is 16% bigger than a 4 carat round (10.2 mm).
There is no rule. The stone is 55% of the width of a size 4 finger and 46% 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