Morganite size chart: carat to mm for every shape

By HeyGema™ · Updated November 5, 2026

In short

A 1 carat round morganite measures about 7.0 mm across, against 6.5 mm for a 1 carat diamond. Morganite is lighter than diamond (2.80 against 3.52), so the same weight gives a bigger stone, 8% wider across.

7.0 mm1 carat round morganite
2.80density, g/cm3
7.5 to 8hardness, Mohs

Carat to mm calculator

ShapeGemCarat

About 7.0 x 7.0 mm

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

Morganite size chart: carat to mm

Face-up length and width in mm of a well-cut morganite at each weight and shape. Morganite is lighter than diamond (2.80 against 3.52), so the same weight gives a bigger stone, 8% wider across.

Weight	Round	Oval	Cushion	Emerald cut	Pear	Princess
0.25 ct	4.4	5.4 x 3.7	3.8 x 3.8	4.8 x 3.4	5.8 x 3.7	3.7 x 3.7
0.5 ct	5.5	6.9 x 4.7	4.8 x 4.8	6.0 x 4.3	7.3 x 4.7	4.7 x 4.7
0.75 ct	6.3	7.8 x 5.4	5.5 x 5.5	6.9 x 4.9	8.3 x 5.4	5.4 x 5.4
1 ct	7.0	8.6 x 5.9	6.0 x 6.0	7.6 x 5.4	9.2 x 5.9	5.9 x 5.9
1.5 ct	8.0	9.9 x 6.8	6.9 x 6.9	8.6 x 6.2	10.5 x 6.8	6.8 x 6.8
2 ct	8.8	10.9 x 7.5	7.6 x 7.6	9.5 x 6.8	11.6 x 7.5	7.5 x 7.5
3 ct	10.0	12.5 x 8.6	8.7 x 8.7	10.9 x 7.8	13.2 x 8.6	8.6 x 8.6
4 ct	11.1	13.7 x 9.4	9.6 x 9.6	12.0 x 8.6	14.6 x 9.4	9.4 x 9.4
5 ct	11.9	14.8 x 10.2	10.3 x 10.3	12.9 x 9.2	15.7 x 10.2	10.2 x 10.2
10 ct	15.0	18.6 x 12.8	13.0 x 13.0	16.3 x 11.6	19.8 x 12.8	12.8 x 12.8

Length x width in mm. A round stone shows one number, its diameter.

mm to carat for a round morganite

If you know the size, this is the weight. Measure across the widest point of the stone, face up.

4 mm: Weight: 0.19 ct

5 mm: Weight: 0.37 ct

6 mm: Weight: 0.64 ct

7 mm: Weight: 1.02 ct

8 mm: Weight: 1.52 ct

9 mm: Weight: 2.16 ct

10 mm: Weight: 2.96 ct

12 mm: Weight: 5.12 ct

Diameter	Weight
4 mm	0.19 ct
5 mm	0.37 ct
6 mm	0.64 ct
7 mm	1.02 ct
8 mm	1.52 ct
9 mm	2.16 ct
10 mm	2.96 ct
12 mm	5.12 ct

Morganite against diamond

How wide a round morganite is next to a round diamond of the same weight.

0.5 ct: Morganite: 5.5 mm; Diamond: 5.1 mm; Difference: +0.4 mm

1 ct: Morganite: 7.0 mm; Diamond: 6.5 mm; Difference: +0.5 mm

2 ct: Morganite: 8.8 mm; Diamond: 8.1 mm; Difference: +0.6 mm

3 ct: Morganite: 10.0 mm; Diamond: 9.3 mm; Difference: +0.7 mm

5 ct: Morganite: 11.9 mm; Diamond: 11.0 mm; Difference: +0.9 mm

Weight	Morganite	Diamond	Difference
0.5 ct	5.5 mm	5.1 mm	+0.4 mm
1 ct	7.0 mm	6.5 mm	+0.5 mm
2 ct	8.8 mm	8.1 mm	+0.6 mm
3 ct	10.0 mm	9.3 mm	+0.7 mm
5 ct	11.9 mm	11.0 mm	+0.9 mm

Morganite properties

Density used in the charts: Value: 2.80 g/cm3 (range 2.80 to 2.90)

Hardness (Mohs): Value: 7.5 to 8

Refractive index: Value: 1.572 to 1.600

Property	Value
Density used in the charts	2.80 g/cm3 (range 2.80 to 2.90)
Hardness (Mohs)	7.5 to 8
Refractive index	1.572 to 1.600

A pink to peach beryl. A little denser than emerald or aquamarine, still lighter than diamond.

Morganite at each weight

Questions

A 1 carat round morganite is about 7.0 mm across. An oval is 8.6 x 5.9 mm and a cushion cut 6.0 x 6.0 mm.

Yes. A 1 carat morganite is 7.0 mm and a 1 carat diamond 6.5 mm. Morganite is lighter than diamond (2.80 against 3.52), so the same weight gives a bigger stone, 8% wider across.

A 6 mm round morganite weighs about 0.64 carat. An 8 mm stone weighs about 1.52 carat.

A 5 carat round morganite is about 11.9 mm across (0.47 inches).

A carat is a weight, 0.2 grams. Gems differ in density, so a gram of a dense gem takes up less space than a gram of a light one. Dense stones face up smaller for their weight.