How big is a 3 carat amethyst?
By HeyGema™ · Updated
In short
A 3 carat round amethyst measures about 10.2 mm across (0.40 inches), 10% wider than a 3 carat diamond (9.3 mm). An oval of the same weight is 12.7 x 8.7 mm and an emerald cut 11.1 x 7.9 mm.
- 10.2 mmround amethyst, across
- 0.40 inthe same in inches
- 0.60 gweight
- 62%of a size 6 finger's width
Carat to mm calculator
About 10.2 x 10.2 mm
An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.
Round
10.2 mm
Oval
12.7 x 8.7 mm
Cushion
8.9 x 8.9 mm
Princess
8.7 x 8.7 mm
Emerald cut
11.1 x 7.9 mm
Asscher
8.7 x 8.7 mm
Radiant
10.3 x 7.9 mm
Pear
13.5 x 8.7 mm
Marquise
16.5 x 8.2 mm
Heart
10.3 x 10.3 mm
Trillion
11.1 x 11.1 mm
Baguette
12.7 x 6.3 mm
= 5 mm in every picture above
3 carat amethyst size by shape
Face-up measurements of a well-cut 3 carat amethyst. Amethyst is lighter than diamond (2.65 against 3.52), so the same weight gives a bigger stone, 10% wider across.
- Round
- Length x width: 10.2 mm
- In inches: 0.40 in
- Oval
- Length x width: 12.7 x 8.7 mm
- In inches: 0.50 x 0.34 in
- Cushion
- Length x width: 8.9 x 8.9 mm
- In inches: 0.35 x 0.35 in
- Princess
- Length x width: 8.7 x 8.7 mm
- In inches: 0.34 x 0.34 in
- Emerald cut
- Length x width: 11.1 x 7.9 mm
- In inches: 0.44 x 0.31 in
- Asscher
- Length x width: 8.7 x 8.7 mm
- In inches: 0.34 x 0.34 in
- Radiant
- Length x width: 10.3 x 7.9 mm
- In inches: 0.41 x 0.31 in
- Pear
- Length x width: 13.5 x 8.7 mm
- In inches: 0.53 x 0.34 in
- Marquise
- Length x width: 16.5 x 8.2 mm
- In inches: 0.65 x 0.32 in
- Heart
- Length x width: 10.3 x 10.3 mm
- In inches: 0.41 x 0.41 in
- Trillion
- Length x width: 11.1 x 11.1 mm
- In inches: 0.44 x 0.44 in
- Baguette
- Length x width: 12.7 x 6.3 mm
- In inches: 0.50 x 0.25 in
3 carat amethyst against other gems
- Diamond
- Round, 3 carat: 9.3 mm
- Moissanite
- Round, 3 carat: 9.6 mm
- Sapphire
- Round, 3 carat: 8.9 mm
- Ruby
- Round, 3 carat: 8.9 mm
- Emerald
- Round, 3 carat: 10.1 mm
- Aquamarine
- Round, 3 carat: 10.2 mm
- Morganite
- Round, 3 carat: 10.0 mm
- Tanzanite
- Round, 3 carat: 9.5 mm
- Amethyst (this page)
- Round, 3 carat: 10.2 mm
3 carat amethyst on a finger
- 4
- Finger width: 14.9 mm
- Round covers: 69%
- Oval covers: 59%
- 5
- Finger width: 15.7 mm
- Round covers: 65%
- Oval covers: 56%
- 6
- Finger width: 16.5 mm
- Round covers: 62%
- Oval covers: 53%
- 7
- Finger width: 17.3 mm
- Round covers: 59%
- Oval covers: 50%
- 8
- Finger width: 18.1 mm
- Round covers: 56%
- Oval covers: 48%
- 9
- Finger width: 18.9 mm
- Round covers: 54%
- Oval covers: 46%
Amethyst at nearby weights
- 2 carat amethyst
- Round diameter: 8.9 mm
- 3 ct (this page)
- Round diameter: 10.2 mm
- 4 carat amethyst
- Round diameter: 11.3 mm
Questions
A round 3 carat amethyst is about 10.2 mm across. Other shapes are longer than they are wide: an oval is 12.7 x 8.7 mm.
Yes. A round 3 carat amethyst is 10% wider than a 3 carat diamond (9.3 mm).
0.60 grams. A carat is 200 milligrams for every gem.
A round 3 carat amethyst covers 62% of the width of a size 6 finger. Compare it with a ring you have tried on in the finger chart above.