Moissanite & Diamond Size Chart

Carat is a measure of weight, not size, so the best way to picture a stone is by its measurements in millimetres. This chart shows the typical face-up size of each shape at common carat weights, and explains how carat labels work for moissanite. Every Bhumi Gems listing also gives the stone's own measurements.

Size chart by shape

Typical face-up sizes in millimetres. Exact sizes depend on each stone's proportions and, for elongated shapes, its length-to-width ratio.

Shape	1 ct	1.5 ct	2 ct	3 ct
Round	6.5	7.4	8.1	9.3
Oval	7.7 x 5.7	8.8 x 6.5	9.8 x 7.2	11 x 8
Emerald	7 x 5	7.8 x 5.6	8.5 x 6.3	9.5 x 7
Pear	8 x 5	9 x 6	10 x 6.5	11.5 x 7.5
Marquise	10 x 5	11 x 5.5	12 x 6	14 x 7
Princess	5.5	6.3	6.9	7.9
Cushion (square)	5.5 to 6	6.5	7 to 7.3	8 to 8.3
Radiant	6 x 5.5	6.8 x 6	7.5 x 6.5	8.5 x 7.3
Asscher	5.5	6.3	7	8

Which shapes look biggest?

Long, shallow shapes spread their weight across the finger. For the same carat weight, a marquise looks the largest, followed by pear and oval. Deeper shapes such as Asscher and cushion hold more weight below the surface, so they look a little smaller from the top. Round sits in the middle.

How carat labels work for moissanite

Moissanite is lighter than diamond: it weighs roughly 9 to 10 percent less for the same size. A 6.5 mm round moissanite, the same size as a 1 ct round diamond, actually weighs about 0.9 ct. To make comparison easy, moissanite is usually labelled by its diamond-equivalent size, so a moissanite sold as "1 ct" is the size of a 1 ct diamond. That is why we always give millimetre measurements: they tell you exactly how big the stone is, whichever gem it is.

Lab grown diamonds are diamond, so their carat weight and size match the chart above directly.

How big will it look on the hand?

• On a typical US size 6 finger, a 1 ct round covers about a third of the finger's width; a 2 ct round covers close to half.
• A halo adds about 1.5 to 2 mm of sparkle around the centre stone, so a 1 ct centre with a halo can look closer to a 1.5 to 2 ct stone.
• Slim bands make the centre stone look larger; wide bands make it look smaller.

Earrings and pendants

Earrings are labelled by carat total weight (ct tw) for the pair, so a 2 ct tw pair has two stones of about 1 ct each, around 6.5 mm across if round. A pendant is seen from further away than a ring, so a stone that looks large on the finger looks more modest at the neck.

Planning a custom piece

Send us your preferred shape, millimetre size, stone (moissanite or lab grown diamond), metal and ring size, and we will confirm the measurements for your design before you order. Start on our custom jewelry page, or browse loose moissanite stones.

More help: ring size guide, 2 carat lab grown diamond rings and oval vs round.