How big is a 1 carat marquise diamond?

By HeyGema™ · Updated

In short

A 1 carat marquise diamond measures about 10.4 x 5.2 mm. It faces up 16% bigger than a round diamond of the same weight. On a size 6 finger it covers 32% of the width. For the same weight, a round diamond is 6.5 mm.

Carat to mm calculator

About 10.4 x 5.2 mm

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

1 ct marquise
10.4 x 5.2 mm
1 ct round
6.5 mm
Side by side
1 ct round inside 1 ct marquise
A 1 carat marquise diamond beside a 1 carat round, to the same scale.

1 carat marquise diamond size

A well-cut 1 carat marquise diamond measures about 10.4 x 5.2 mm (0.41 x 0.20 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 0.20 grams.

1 carat marquise size by length-to-width ratio

The same weight can be long and narrow or short and wide. These are 1 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: 9.9 x 5.5 mm
Width on the finger: 33% of a size 6 finger
2.00:1
Length x width: 10.4 x 5.2 mm
Width on the finger: 32% of a size 6 finger
2.20:1
Length x width: 10.9 x 5.0 mm
Width on the finger: 30% of a size 6 finger

1 carat marquise on a finger

5.2 mm
5.2 mm stone on a 16.5 mm finger: it covers 32% of the widthA 1 carat marquise diamond on a size 6 finger.
4
Finger width: 14.9 mm
Marquise covers: 35%
5
Finger width: 15.7 mm
Marquise covers: 33%
6
Finger width: 16.5 mm
Marquise covers: 32%
7
Finger width: 17.3 mm
Marquise covers: 30%
8
Finger width: 18.1 mm
Marquise covers: 29%
9
Finger width: 18.9 mm
Marquise covers: 27%

Marquise sizes near 1 carat

0.5 carat
Length x width: 8.3 x 4.1 mm
Round of the same weight: 5.1 mm
0.75 carat
Length x width: 9.4 x 4.7 mm
Round of the same weight: 5.9 mm
1 (this page)
Length x width: 10.4 x 5.2 mm
Round of the same weight: 6.5 mm
1.25 carat
Length x width: 11.2 x 5.6 mm
Round of the same weight: 6.9 mm
1.5 carat
Length x width: 11.9 x 6.0 mm
Round of the same weight: 7.4 mm

1 carat in other shapes

Every row is a well-cut diamond of 1 carat. The last column is the face-up size against the marquise.

Round
Length x width: 6.5 mm
Against marquise: -14%
Oval
Length x width: 8.0 x 5.5 mm
Against marquise: -9%
Cushion
Length x width: 5.6 x 5.6 mm
Against marquise: -26%
Princess
Length x width: 5.5 x 5.5 mm
Against marquise: -21%
Emerald cut
Length x width: 7.0 x 5.0 mm
Against marquise: -10%
Asscher
Length x width: 5.5 x 5.5 mm
Against marquise: -27%
Radiant
Length x width: 6.5 x 5.0 mm
Against marquise: -16%
Pear
Length x width: 8.5 x 5.5 mm
Against marquise: -16%
Heart
Length x width: 6.5 x 6.5 mm
Against marquise: -28%
Trillion
Length x width: 7.0 x 7.0 mm
Against marquise: -25%
Baguette
Length x width: 8.0 x 4.0 mm
Against marquise: -15%

Questions

A 1 carat marquise diamond is about 10.4 x 5.2 mm at the usual 2.00:1 ratio.
Yes. Face-up, a 1 carat marquise is 16% bigger than a 1 carat round (6.5 mm).
There is no rule. The stone is 35% of the width of a size 4 finger and 29% 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