Moissanite is lighter than diamond, so we describe stone size in millimetres and in Diamond Equivalent Weight (DEW), the carat weight a diamond of the same size would have. Figures are approximate.

Round brilliant

Diameter	Approx. DEW
4.0 mm	0.25 ct
5.0 mm	0.45 ct
5.5 mm	0.60 ct
6.5 mm	1.00 ct
7.0 mm	1.25 ct
7.5 mm	1.60 ct
8.0 mm	2.00 ct
9.0 mm	2.75 ct
9.5 mm	3.00 ct

Pear cut

Size	Approx. DEW
8 x 5 mm	0.75 ct
8 x 6 mm	0.90 ct
9 x 6 mm	1.00 ct
10 x 7 mm	1.50 ct
12 x 8 mm	2.50 ct

Radiant and emerald cut

Size	Approx. DEW
7 x 5 mm	1.00 ct
8 x 6 mm	1.50 ct
9 x 7 mm	2.50 ct