How many carats is a 1.5 mm diamond?

By HeyGema™ · Updated November 5, 2026

In short

A 1.5 mm round diamond weighs about 0.013 carat (0.003 grams). A 1.5 mm princess cut weighs about 0.020 carat, and an oval that is 1.5 mm long about 0.010 carat.

0.013 ctround diamond, 1.5 mm
0.003 gweight
0.06 in1.5 mm in inches

Carat to mm calculator

ShapeGemLength (mm)

About 0.01 carat

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

1.5 mm diamond weight by shape

The weight of a well-cut diamond measuring 1.5 mm. For round and square shapes the number is the diameter or the side. For longer shapes it is the long side, with the width following the usual ratio.

Round: Size: 1.5 mm; Weight: 0.013 ct

Oval: Size: 1.5 mm x 1.03 mm; Weight: 0.0070 ct

Cushion: Size: 1.5 mm x 1.50 mm; Weight: 0.019 ct

Princess: Size: 1.5 mm x 1.50 mm; Weight: 0.020 ct

Emerald cut: Size: 1.5 mm x 1.07 mm; Weight: 0.010 ct

Asscher: Size: 1.5 mm x 1.50 mm; Weight: 0.020 ct

Radiant: Size: 1.5 mm x 1.15 mm; Weight: 0.012 ct

Pear: Size: 1.5 mm x 0.97 mm; Weight: 0.0050 ct

Marquise: Size: 1.5 mm x 0.75 mm; Weight: 0.0030 ct

Heart: Size: 1.5 mm x 1.50 mm; Weight: 0.012 ct

Trillion: Size: 1.5 mm x 1.50 mm; Weight: 0.010 ct

Baguette: Size: 1.5 mm x 0.75 mm; Weight: 0.0070 ct

Shape	Size	Weight
Round	1.5 mm	0.013 ct
Oval	1.5 mm x 1.03 mm	0.0070 ct
Cushion	1.5 mm x 1.50 mm	0.019 ct
Princess	1.5 mm x 1.50 mm	0.020 ct
Emerald cut	1.5 mm x 1.07 mm	0.010 ct
Asscher	1.5 mm x 1.50 mm	0.020 ct
Radiant	1.5 mm x 1.15 mm	0.012 ct
Pear	1.5 mm x 0.97 mm	0.0050 ct
Marquise	1.5 mm x 0.75 mm	0.0030 ct
Heart	1.5 mm x 1.50 mm	0.012 ct
Trillion	1.5 mm x 1.50 mm	0.010 ct
Baguette	1.5 mm x 0.75 mm	0.0070 ct

1.5 mm stones in other gems

A round stone of the same size weighs differently in each gem, because gems differ in density.

Diamond: Weight of a round stone: 0.013 ct

Moissanite: Weight of a round stone: 0.012 ct

Sapphire: Weight of a round stone: 0.014 ct

Ruby: Weight of a round stone: 0.014 ct

Emerald: Weight of a round stone: 0.010 ct

Aquamarine: Weight of a round stone: 0.010 ct

Topaz: Weight of a round stone: 0.013 ct

Amethyst: Weight of a round stone: 0.0090 ct

Spinel: Weight of a round stone: 0.013 ct

Tanzanite: Weight of a round stone: 0.012 ct

Morganite: Weight of a round stone: 0.010 ct

Gem	Weight of a round stone
Diamond	0.013 ct
Moissanite	0.012 ct
Sapphire	0.014 ct
Ruby	0.014 ct
Emerald	0.010 ct
Aquamarine	0.010 ct
Topaz	0.013 ct
Amethyst	0.0090 ct
Spinel	0.013 ct
Tanzanite	0.012 ct
Morganite	0.010 ct

1.5 mm diamond studs

A pair of 1.5 mm round diamond studs has a total carat weight of about 0.025 carat, 0.013 carat for each stone. See the diamond stud earring size chart.

Nearby sizes

1 mm: Weight: 0.0040 ct; Inches: 0.04 in

1.5 mm (this page): Weight: 0.013 ct; Inches: 0.06 in

2 mm: Weight: 0.030 ct; Inches: 0.08 in

2.5 mm: Weight: 0.058 ct; Inches: 0.10 in

Diameter	Weight	Inches
1 mm	0.0040 ct	0.04 in
1.5 mm (this page)	0.013 ct	0.06 in
2 mm	0.030 ct	0.08 in
2.5 mm	0.058 ct	0.10 in

Questions

About 0.013 carat for a well-cut round diamond.

A 1.5 mm princess cut, measured along one side, weighs about 0.020 carat.

A 1.5 mm round moissanite is labeled 0.013 carat (diamond equivalent weight) and weighs about 0.010 carat. See the moissanite size chart.

1.5 mm is 0.06 inches.