0.5 carat vs 1 carat diamond size
By HeyGema™ · Updated
In short
A round 1 carat diamond measures 6.5 mm and a round 0.5 carat 5.1 mm. The 1 carat is twice the weight but only 26% wider (1.3 mm), with 59% more face-up area.
- 5.1 vs 6.5 mmround diameter
- 26%wider at 1 ct
- 59%more face-up area
Carat to mm calculator
About 6.5 x 6.5 mm
An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.
0.5 carat vs 1 carat: how much bigger is it?
A 1 carat diamond weighs twice the weight of a 0.5 carat, but it is only 26% wider. A round 0.5 carat measures 5.1 mm and a round 1 carat 6.5 mm, a difference of 1.3 mm. Seen from above, the 1 carat covers 59% 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.
0.5 carat and 1 carat in every shape
- Round
- 0.5 carat: 5.1 mm
- 1 carat: 6.5 mm
- Longer by: 1.3 mm
- Oval
- 0.5 carat: 6.3 x 4.4 mm
- 1 carat: 8.0 x 5.5 mm
- Longer by: 1.7 mm
- Cushion
- 0.5 carat: 4.4 x 4.4 mm
- 1 carat: 5.6 x 5.6 mm
- Longer by: 1.2 mm
- Princess
- 0.5 carat: 4.4 x 4.4 mm
- 1 carat: 5.5 x 5.5 mm
- Longer by: 1.1 mm
- Emerald cut
- 0.5 carat: 5.6 x 4.0 mm
- 1 carat: 7.0 x 5.0 mm
- Longer by: 1.4 mm
- Pear
- 0.5 carat: 6.7 x 4.4 mm
- 1 carat: 8.5 x 5.5 mm
- Longer by: 1.8 mm
- Marquise
- 0.5 carat: 8.3 x 4.1 mm
- 1 carat: 10.4 x 5.2 mm
- Longer by: 2.1 mm
- Radiant
- 0.5 carat: 5.2 x 4.0 mm
- 1 carat: 6.5 x 5.0 mm
- Longer by: 1.3 mm
- Asscher
- 0.5 carat: 4.4 x 4.4 mm
- 1 carat: 5.5 x 5.5 mm
- Longer by: 1.1 mm
- Heart
- 0.5 carat: 5.2 x 5.2 mm
- 1 carat: 6.5 x 6.5 mm
- Longer by: 1.3 mm
0.5 carat vs 1 carat on a finger
- 4
- Finger width: 14.9 mm
- Round 0.5 ct covers: 34%
- Round 1 ct covers: 43%
- 5
- Finger width: 15.7 mm
- Round 0.5 ct covers: 33%
- Round 1 ct covers: 41%
- 6
- Finger width: 16.5 mm
- Round 0.5 ct covers: 31%
- Round 1 ct covers: 39%
- 7
- Finger width: 17.3 mm
- Round 0.5 ct covers: 30%
- Round 1 ct covers: 37%
- 8
- Finger width: 18.1 mm
- Round 0.5 ct covers: 28%
- Round 1 ct covers: 36%
On a size 6 finger the 0.5 carat reads as classic (31% of the width) and the 1 carat as classic (39%). 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 0.5 and 1 carat
Shape changes the picture. An oval or a pear of 0.5 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.