How big is a 6 carat marquise diamond?

By HeyGema™ · Updated

In short

A 6 carat marquise diamond measures about 18.9 x 9.4 mm. It faces up 16% bigger than a round diamond of the same weight. On a size 6 finger it covers 57% of the width. For the same weight, a round diamond is 11.7 mm.

Carat to mm calculator

About 18.9 x 9.4 mm

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

6 ct marquise
18.9 x 9.4 mm
6 ct round
11.7 mm
Side by side
6 ct round inside 6 ct marquise
A 6 carat marquise diamond beside a 6 carat round, to the same scale.

6 carat marquise diamond size

A well-cut 6 carat marquise diamond measures about 18.9 x 9.4 mm (0.74 x 0.37 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 1.20 grams.

6 carat marquise size by length-to-width ratio

The same weight can be long and narrow or short and wide. These are 6 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: 17.9 x 10.0 mm
Width on the finger: 60% of a size 6 finger
2.00:1
Length x width: 18.9 x 9.4 mm
Width on the finger: 57% of a size 6 finger
2.20:1
Length x width: 19.8 x 9.0 mm
Width on the finger: 55% of a size 6 finger

6 carat marquise on a finger

9.4 mm
9.4 mm stone on a 16.5 mm finger: it covers 57% of the widthA 6 carat marquise diamond on a size 6 finger.
4
Finger width: 14.9 mm
Marquise covers: 63%
5
Finger width: 15.7 mm
Marquise covers: 60%
6
Finger width: 16.5 mm
Marquise covers: 57%
7
Finger width: 17.3 mm
Marquise covers: 55%
8
Finger width: 18.1 mm
Marquise covers: 52%
9
Finger width: 18.9 mm
Marquise covers: 50%

Marquise sizes near 6 carat

4 carat
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 (this page)
Length x width: 18.9 x 9.4 mm
Round of the same weight: 11.7 mm
8 carat
Length x width: 20.8 x 10.4 mm
Round of the same weight: 12.9 mm
10 carat
Length x width: 22.4 x 11.2 mm
Round of the same weight: 13.9 mm

6 carat in other shapes

Every row is a well-cut diamond of 6 carat. The last column is the face-up size against the marquise.

Round
Length x width: 11.7 mm
Against marquise: -14%
Oval
Length x width: 14.5 x 10.0 mm
Against marquise: -9%
Cushion
Length x width: 10.2 x 10.2 mm
Against marquise: -26%
Princess
Length x width: 10.0 x 10.0 mm
Against marquise: -21%
Emerald cut
Length x width: 12.7 x 9.1 mm
Against marquise: -10%
Asscher
Length x width: 10.0 x 10.0 mm
Against marquise: -27%
Radiant
Length x width: 11.8 x 9.1 mm
Against marquise: -16%
Pear
Length x width: 15.4 x 10.0 mm
Against marquise: -16%
Heart
Length x width: 11.8 x 11.8 mm
Against marquise: -28%
Trillion
Length x width: 12.7 x 12.7 mm
Against marquise: -25%
Baguette
Length x width: 14.5 x 7.3 mm
Against marquise: -15%

Questions

A 6 carat marquise diamond is about 18.9 x 9.4 mm at the usual 2.00:1 ratio.
Yes. Face-up, a 6 carat marquise is 16% bigger than a 6 carat round (11.7 mm).
There is no rule. The stone is 63% of the width of a size 4 finger and 52% 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