Cabochon-cut Ruby Size Chart
Carat to mm size chart for cabochon-cut Ruby, from 0.25ct to 40ct (at an L/W ratio of 1.5). The chart is interactive, meaning you can click on any stone to view it directly in the size simulator.
Gem sizes are shown in actual, real-world size, provided your device screen size is in diagonal. If this is not correct, change it here:
Gem sizes are shown in actual, real-world size, provided your device screen size is in diagonal. If this is not correct, change it here:
Actual size is set for screen
Gemstone:
Shape:
Ruby Size Chart (Cabochon Cut)
0.25ct
4.31×2.87 mm
4.31×2.87 mm
0.5ct
5.43×3.62 mm
5.43×3.62 mm
0.75ct
6.23×4.15 mm
6.23×4.15 mm
1ct
6.84×4.56 mm
6.84×4.56 mm
1.25ct
7.37×4.91 mm
7.37×4.91 mm
1.5ct
7.83×5.22 mm
7.83×5.22 mm
1.75ct
8.25×5.5 mm
8.25×5.5 mm
2ct
8.63×5.75 mm
8.63×5.75 mm
2.5ct
9.29×6.19 mm
9.29×6.19 mm
3ct
9.87×6.58 mm
9.87×6.58 mm
3.5ct
10.4×6.93 mm
10.4×6.93 mm
4ct
10.86×7.24 mm
10.86×7.24 mm
4.5ct
11.3×7.53 mm
11.3×7.53 mm
5ct
11.7×7.8 mm
11.7×7.8 mm
5.5ct
12.08×8.05 mm
12.08×8.05 mm
6ct
12.44×8.29 mm
12.44×8.29 mm
6.5ct
12.77×8.51 mm
12.77×8.51 mm
7ct
13.1×8.73 mm
13.1×8.73 mm
7.5ct
13.4×8.93 mm
13.4×8.93 mm
8ct
13.68×9.12 mm
13.68×9.12 mm
8.5ct
13.97×9.31 mm
13.97×9.31 mm
9ct
14.24×9.49 mm
14.24×9.49 mm
9.5ct
14.49×9.66 mm
14.49×9.66 mm
10ct
14.75×9.83 mm
14.75×9.83 mm
11ct
15.23×10.15 mm
15.23×10.15 mm
12ct
15.68×10.45 mm
15.68×10.45 mm
13ct
16.1×10.73 mm
16.1×10.73 mm
14ct
16.5×11 mm
16.5×11 mm
15ct
16.88×11.25 mm
16.88×11.25 mm
16ct
17.25×11.5 mm
17.25×11.5 mm
17ct
17.6×11.73 mm
17.6×11.73 mm
18ct
17.94×11.96 mm
17.94×11.96 mm
19ct
18.26×12.17 mm
18.26×12.17 mm
20ct
18.57×12.38 mm
18.57×12.38 mm
22ct
19.17×12.78 mm
19.17×12.78 mm
24ct
19.74×13.16 mm
19.74×13.16 mm
26ct
20.28×13.52 mm
20.28×13.52 mm
28ct
20.78×13.85 mm
20.78×13.85 mm
30ct
21.27×14.18 mm
21.27×14.18 mm
33ct
21.95×14.63 mm
21.95×14.63 mm
36ct
22.59×15.06 mm
22.59×15.06 mm
40ct
23.4×15.6 mm
23.4×15.6 mm
Length-to-width ratio: 1.5, Color:
Download Chart
Note: If you want to cut out the shapes and try them on your finger, print out the PDF chart. The image (png) chart will not print at actual size.
Carat-to-MM Conversion Table
Use this conversion table to quickly convert cabochon-cut Ruby carat weights to their approximate millimeter (mm) sizes:
| Carat Weight | MM Size |
|---|---|
| 0.25 ct | 4.31×2.87 mm |
| 0.5 ct | 5.43×3.62 mm |
| 0.75 ct | 6.23×4.15 mm |
| 1 ct | 6.84×4.56 mm |
| 1.25 ct | 7.37×4.91 mm |
| 1.5 ct | 7.83×5.22 mm |
| 1.75 ct | 8.25×5.5 mm |
| 2 ct | 8.63×5.75 mm |
| 2.5 ct | 9.29×6.19 mm |
| 3 ct | 9.87×6.58 mm |
| 3.5 ct | 10.4×6.93 mm |
| 4 ct | 10.86×7.24 mm |
| 4.5 ct | 11.3×7.53 mm |
| 5 ct | 11.7×7.8 mm |
| 5.5 ct | 12.08×8.05 mm |
| 6 ct | 12.44×8.29 mm |
| 6.5 ct | 12.77×8.51 mm |
| 7 ct | 13.1×8.73 mm |
| 7.5 ct | 13.4×8.93 mm |
| 8 ct | 13.68×9.12 mm |
| 8.5 ct | 13.97×9.31 mm |
| Carat Weight | MM Size |
|---|---|
| 9 ct | 14.24×9.49 mm |
| 9.5 ct | 14.49×9.66 mm |
| 10 ct | 14.75×9.83 mm |
| 11 ct | 15.23×10.15 mm |
| 12 ct | 15.68×10.45 mm |
| 13 ct | 16.1×10.73 mm |
| 14 ct | 16.5×11 mm |
| 15 ct | 16.88×11.25 mm |
| 16 ct | 17.25×11.5 mm |
| 17 ct | 17.6×11.73 mm |
| 18 ct | 17.94×11.96 mm |
| 19 ct | 18.26×12.17 mm |
| 20 ct | 18.57×12.38 mm |
| 22 ct | 19.17×12.78 mm |
| 24 ct | 19.74×13.16 mm |
| 26 ct | 20.28×13.52 mm |
| 28 ct | 20.78×13.85 mm |
| 30 ct | 21.27×14.18 mm |
| 33 ct | 21.95×14.63 mm |
| 36 ct | 22.59×15.06 mm |
| 40 ct | 23.4×15.6 mm |