1.5 carat vs 2 carat diamond size

By HeyGema™ · Updated

In short

A round 2 carat diamond measures 8.1 mm and a round 1.5 carat 7.4 mm. The 2 carat is 1.33 times the weight but only 10% wider (0.7 mm), with 21% more face-up area.

Carat to mm calculator

About 8.1 x 8.1 mm

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

1.5 carat
7.4 mm
2 carat
8.1 mm
Side by side
1.5 carat inside 2 carat
A 1.5 carat and a 2 carat round diamond, to the same scale. The dashed outline is the 1.5 carat stone inside the 2 carat one.

1.5 carat vs 2 carat: how much bigger is it?

A 2 carat diamond weighs 1.33 times the weight of a 1.5 carat, but it is only 10% wider. A round 1.5 carat measures 7.4 mm and a round 2 carat 8.1 mm, a difference of 0.7 mm. Seen from above, the 2 carat covers 21% more area.

The gap is smaller than the weights suggest because carats measure weight, which grows with volume. A stone that is twice as heavy is the cube root of two (1.26 times) as wide, not twice as wide.

1.5 carat and 2 carat in every shape

Round
1.5 carat: 7.4 mm
2 carat: 8.1 mm
Longer by: 0.7 mm
Oval
1.5 carat: 9.2 x 6.3 mm
2 carat: 10.1 x 6.9 mm
Longer by: 0.9 mm
Cushion
1.5 carat: 6.4 x 6.4 mm
2 carat: 7.1 x 7.1 mm
Longer by: 0.6 mm
Princess
1.5 carat: 6.3 x 6.3 mm
2 carat: 6.9 x 6.9 mm
Longer by: 0.6 mm
Emerald cut
1.5 carat: 8.0 x 5.7 mm
2 carat: 8.8 x 6.3 mm
Longer by: 0.8 mm
Pear
1.5 carat: 9.7 x 6.3 mm
2 carat: 10.7 x 6.9 mm
Longer by: 1.0 mm
Marquise
1.5 carat: 11.9 x 6.0 mm
2 carat: 13.1 x 6.6 mm
Longer by: 1.2 mm
Radiant
1.5 carat: 7.4 x 5.7 mm
2 carat: 8.2 x 6.3 mm
Longer by: 0.7 mm
Asscher
1.5 carat: 6.3 x 6.3 mm
2 carat: 6.9 x 6.9 mm
Longer by: 0.6 mm
Heart
1.5 carat: 7.4 x 7.4 mm
2 carat: 8.2 x 8.2 mm
Longer by: 0.7 mm

1.5 carat vs 2 carat on a finger

8.1 mm
8.1 mm stone on a 16.5 mm finger: it covers 49% of the widthA round 2 carat diamond on a size 6 finger. A round 1.5 carat covers 45% of the same finger.
4
Finger width: 14.9 mm
Round 1.5 ct covers: 50%
Round 2 ct covers: 55%
5
Finger width: 15.7 mm
Round 1.5 ct covers: 47%
Round 2 ct covers: 52%
6
Finger width: 16.5 mm
Round 1.5 ct covers: 45%
Round 2 ct covers: 49%
7
Finger width: 17.3 mm
Round 1.5 ct covers: 43%
Round 2 ct covers: 47%
8
Finger width: 18.1 mm
Round 1.5 ct covers: 41%
Round 2 ct covers: 45%

On a size 6 finger the 1.5 carat reads as bold (45% of the width) and the 2 carat as bold (49%). The bands are our own: delicate is under 30% of the finger's width, classic is 30% to 44%, bold is 45% to 59%, statement is 60% and more.

Other cuts at 1.5 and 2 carat

Shape changes the picture. An oval or a pear of 1.5 carat can face up as large as a round of a higher weight. See the shapes that look biggest, or compare any two stones with the size comparison tool.

Questions

A round 2 carat is 8.1 mm against 7.4 mm for a 1.5 carat: 10% wider and 21% larger face-up, for 1.33 times the weight.
Size and weight do not scale together. Weight follows volume, so every side of the stone grows with the cube root of the weight. 1.33 times the weight is 10% wider.
The difference is 0.7 mm across a round stone. On a size 6 finger that is 45% of the width against 49%. Setting, shape and cut change how big either stone looks, so look at both in the shape you like.
1.5 carat round: 7.4 mm (0.29 in). 2 carat round: 8.1 mm (0.32 in). They weigh 0.30 g and 0.40 g.

More size charts