How big is a 1 carat opal?
By HeyGema™ · Updated
In short
A 1 carat round opal measures about 7.7 mm across (0.30 inches), 19% wider than a 1 carat diamond (6.5 mm). An oval of the same weight is 9.5 x 6.5 mm and an emerald cut 8.3 x 5.9 mm.
- 7.7 mmround opal, across
- 0.30 inthe same in inches
- 0.20 gweight
- 46%of a size 6 finger's width
Carat to mm calculator
About 7.7 x 7.7 mm
An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.
Round
7.7 mm
Oval
9.5 x 6.5 mm
Cushion
6.7 x 6.7 mm
Princess
6.5 x 6.5 mm
Emerald cut
8.3 x 5.9 mm
Asscher
6.5 x 6.5 mm
Radiant
7.7 x 5.9 mm
Pear
10.1 x 6.5 mm
Marquise
12.4 x 6.2 mm
Heart
7.7 x 7.7 mm
Trillion
8.3 x 8.3 mm
Baguette
9.5 x 4.8 mm
= 5 mm in every picture above
1 carat opal size by shape
Face-up measurements of a well-cut 1 carat opal. Opal is lighter than diamond (2.10 against 3.52), so the same weight gives a bigger stone, 19% wider across.
- Round
- Length x width: 7.7 mm
- In inches: 0.30 in
- Oval
- Length x width: 9.5 x 6.5 mm
- In inches: 0.37 x 0.26 in
- Cushion
- Length x width: 6.7 x 6.7 mm
- In inches: 0.26 x 0.26 in
- Princess
- Length x width: 6.5 x 6.5 mm
- In inches: 0.26 x 0.26 in
- Emerald cut
- Length x width: 8.3 x 5.9 mm
- In inches: 0.33 x 0.23 in
- Asscher
- Length x width: 6.5 x 6.5 mm
- In inches: 0.26 x 0.26 in
- Radiant
- Length x width: 7.7 x 5.9 mm
- In inches: 0.30 x 0.23 in
- Pear
- Length x width: 10.1 x 6.5 mm
- In inches: 0.40 x 0.26 in
- Marquise
- Length x width: 12.4 x 6.2 mm
- In inches: 0.49 x 0.24 in
- Heart
- Length x width: 7.7 x 7.7 mm
- In inches: 0.30 x 0.30 in
- Trillion
- Length x width: 8.3 x 8.3 mm
- In inches: 0.33 x 0.33 in
- Baguette
- Length x width: 9.5 x 4.8 mm
- In inches: 0.37 x 0.19 in
1 carat opal against other gems
- Diamond
- Round, 1 carat: 6.5 mm
- Moissanite
- Round, 1 carat: 6.6 mm
- Sapphire
- Round, 1 carat: 6.2 mm
- Ruby
- Round, 1 carat: 6.2 mm
- Emerald
- Round, 1 carat: 7.0 mm
- Aquamarine
- Round, 1 carat: 7.0 mm
- Morganite
- Round, 1 carat: 7.0 mm
- Tanzanite
- Round, 1 carat: 6.6 mm
- Opal (this page)
- Round, 1 carat: 7.7 mm
1 carat opal on a finger
- 4
- Finger width: 14.9 mm
- Round covers: 51%
- Oval covers: 44%
- 5
- Finger width: 15.7 mm
- Round covers: 49%
- Oval covers: 42%
- 6
- Finger width: 16.5 mm
- Round covers: 46%
- Oval covers: 40%
- 7
- Finger width: 17.3 mm
- Round covers: 44%
- Oval covers: 38%
- 8
- Finger width: 18.1 mm
- Round covers: 42%
- Oval covers: 36%
- 9
- Finger width: 18.9 mm
- Round covers: 40%
- Oval covers: 34%
Opal at nearby weights
- 0.5 carat opal
- Round diameter: 6.1 mm
- 1 ct (this page)
- Round diameter: 7.7 mm
- 1.5 carat opal
- Round diameter: 8.8 mm
Questions
A round 1 carat opal is about 7.7 mm across. Other shapes are longer than they are wide: an oval is 9.5 x 6.5 mm.
Yes. A round 1 carat opal is 19% wider than a 1 carat diamond (6.5 mm).
0.20 grams. A carat is 200 milligrams for every gem.
A round 1 carat opal covers 46% of the width of a size 6 finger. Compare it with a ring you have tried on in the finger chart above.