How big is a 4 carat tourmaline?

By HeyGema™ · Updated

In short

A 4 carat round tourmaline measures about 10.7 mm across (0.42 inches), 5% wider than a 4 carat diamond (10.2 mm). An oval of the same weight is 13.3 x 9.1 mm and an emerald cut 11.6 x 8.3 mm.

Carat to mm calculator

About 10.7 x 10.7 mm

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

Round
10.7 mm
Oval
13.3 x 9.1 mm
Cushion
9.3 x 9.3 mm
Princess
9.1 x 9.1 mm
Emerald cut
11.6 x 8.3 mm
Asscher
9.1 x 9.1 mm
Radiant
10.8 x 8.3 mm
Pear
14.1 x 9.1 mm
Marquise
17.3 x 8.6 mm
Heart
10.8 x 10.8 mm
Trillion
11.6 x 11.6 mm
Baguette
13.3 x 6.7 mm
= 5 mm in every picture above
A 4 carat tourmaline in 12 shapes, drawn to one scale.

4 carat tourmaline size by shape

Face-up measurements of a well-cut 4 carat tourmaline. Tourmaline is lighter than diamond (3.06 against 3.52), so the same weight gives a bigger stone, 5% wider across.

Round
Length x width: 10.7 mm
In inches: 0.42 in
Oval
Length x width: 13.3 x 9.1 mm
In inches: 0.52 x 0.36 in
Cushion
Length x width: 9.3 x 9.3 mm
In inches: 0.37 x 0.37 in
Princess
Length x width: 9.1 x 9.1 mm
In inches: 0.36 x 0.36 in
Emerald cut
Length x width: 11.6 x 8.3 mm
In inches: 0.46 x 0.33 in
Asscher
Length x width: 9.1 x 9.1 mm
In inches: 0.36 x 0.36 in
Radiant
Length x width: 10.8 x 8.3 mm
In inches: 0.43 x 0.33 in
Pear
Length x width: 14.1 x 9.1 mm
In inches: 0.56 x 0.36 in
Marquise
Length x width: 17.3 x 8.6 mm
In inches: 0.68 x 0.34 in
Heart
Length x width: 10.8 x 10.8 mm
In inches: 0.43 x 0.43 in
Trillion
Length x width: 11.6 x 11.6 mm
In inches: 0.46 x 0.46 in
Baguette
Length x width: 13.3 x 6.7 mm
In inches: 0.52 x 0.26 in

4 carat tourmaline against other gems

Diamond
Round, 4 carat: 10.2 mm
Moissanite
Round, 4 carat: 10.5 mm
Sapphire
Round, 4 carat: 9.8 mm
Ruby
Round, 4 carat: 9.8 mm
Emerald
Round, 4 carat: 11.2 mm
Aquamarine
Round, 4 carat: 11.2 mm
Morganite
Round, 4 carat: 11.1 mm
Tanzanite
Round, 4 carat: 10.4 mm
Tourmaline (this page)
Round, 4 carat: 10.7 mm

4 carat tourmaline on a finger

10.7 mm
10.7 mm stone on a 16.5 mm finger: it covers 65% of the widthA round 4 carat tourmaline on a size 6 finger.
4
Finger width: 14.9 mm
Round covers: 72%
Oval covers: 61%
5
Finger width: 15.7 mm
Round covers: 68%
Oval covers: 58%
6
Finger width: 16.5 mm
Round covers: 65%
Oval covers: 55%
7
Finger width: 17.3 mm
Round covers: 62%
Oval covers: 53%
8
Finger width: 18.1 mm
Round covers: 59%
Oval covers: 50%
9
Finger width: 18.9 mm
Round covers: 57%
Oval covers: 48%

Tourmaline at nearby weights

3 carat tourmaline
Round diameter: 9.7 mm
4 ct (this page)
Round diameter: 10.7 mm
5 carat tourmaline
Round diameter: 11.6 mm

Questions

A round 4 carat tourmaline is about 10.7 mm across. Other shapes are longer than they are wide: an oval is 13.3 x 9.1 mm.
Yes. A round 4 carat tourmaline is 5% wider than a 4 carat diamond (10.2 mm).
0.80 grams. A carat is 200 milligrams for every gem.
A round 4 carat tourmaline covers 65% of the width of a size 6 finger. Compare it with a ring you have tried on in the finger chart above.

More size charts