​APPROXIMATE CARAT WEIGHT CHART
​FOR SPECIFIC GEMSTONES (& AVERAGE)

This Approximate Carat Weight Chart for various Gemstone materials in relation to their Shape and millimeter (mm) size serves to help get a ballpark idea of what a carat weight will be. The last column is an average of the various gemstone materials weight for a particular shape and size.  Keep in mind that the individual cutting of any specific gemstone will have a great effect on its resulting carat weight. A shallow stone for example will end up weighing less where a heavy belly cut stone will weigh more.
​​SHAPE/SIZE
ALEXANDRITE
AMETHYST CITRINE
AQUA
DIAMOND
EMERALD
GARNET
OPAL
PERIDOT
RUBY SAPPHIRE
TANZANITE
TOPAZ
TOURMALINE
ZIRCON BLUE
AVERAGE
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
ROUND
2.00mm
0.04
0.04
0.04
0.04
0.04
0.05
0.02
0.05
0.05
0.05
0.04
0.04
0.06
0.05
3.00mm
0.12
0.1
0.1
0.1
0.12
0.13
0.09
0.12
0.15
0.12
0.11
0.12
0.17
0.12
4.00mm
0.35
0.2
0.25
0.23
0.27
0.3
0.16
0.26
0.34
0.29
0.3
0.24
0.36
0.27
5.00mm
0.63
0.4
0.45
0.47
0.48
0.6
0.34
0.5
0.65
0.48
0.56
0.45
0.69
0.53
6.00mm
1.3
0.7
0.75
0.9
0.8
1
0.57
0.85
1.05
0.86
1
0.75
1.25
0.9
7.00mm
2.15
1.3
1.6
1.35
1.7
1.6
0.83
1.25
1.6
1.35
1.55
1.55
1.75
1.51
8.00mm
___
1.8
2.4
1.9
2.5
2.5
1.3
2
2.25
1.85
2.5
2
2.6
2.21
10.00mm
___
3.3
3.5
4.25
6.1
5.75
2
5.25
4.5
3.6
5.75
3
5
4.52
OVAL
ALEXANDRITE
AMETHYST CITRINE
AQUAMARINE
DIAMOND
EMERALD
GARNET
OPAL
PERIDOT
RUBY SAPPHIRE
TANZANITE
TOPAZ
TOURMALINE
ZIRCON BLUE
AVERAGE
5x3mm
0.3
0.23
0.2
0.25
0.28
0.25
0.16
0.28
0.35
0.24
0.27
0.25
0.4
0.28
6x4mm
0.61
0.45
0.4
0.5
0.52
0.55
0.28
0.5
0.6
0.48
0.57
0.5
0.75
0.53
7x5mm
0.8
0.85
0.75
0.75
0.85
1
0.47
0.95
1
0.75
1.1
0.9
1.45
0.95
8x6mm
1.45
1.25
1.1
1.4
1
1.4
0.78
1.35
1.55
1.25
1.6
1.18
2
1.39
9x7mm
2
1.75
1.75
2
1.6
2.1
1.1
2
2.2
1.8
2.5
2.3
2.85
2.08
10x8mm
3.6
2.4
2.25
3
2.25
2.8
1.65
2.5
3.15
2.4
3.5
2.9
4
2.86
11x9mm
4.25
3.24
3
4
3.75
3.75
2.15
3.5
3.8
3.3
4.5
3.5
5.6
3.8
12x10mm
6
4.35
4.5
5
5
5
3
4
6
4.4
6
5.25
7.5
5.25
14x10mm
8.9
5.85
6.75
8
7.5
7
4
6
7.25
5.9
8.8
6.8
8.2
7.1
16x12mm
___
10
10.15
11.5
12
10
5.25
9.5
12
12
12
8.5
13.5
10.93
18x13mm
___
12.38
10.57
16
14.5
13.25
5.75
13
13
14
17
12
14.5
13.46
20x15mm
___
18
14.5
21.5
18
20
9.9
20
20
19
22
18
23
19.42
OCTAGON
ALEXANDRITE
AMETHYST
CITRINE
AQUAMARINE
DIAMOND
​​EMERALD
GARNET
​​OPAL
PERIDOT
RUBY SAPPHIRE
​TANZANITE
TOPAZ
​TOURMALINE
ZIRCON BLUE
AVERAGE
5x3mm
0.4
0.35
0.25
0.25
0.3
0.4
___
0.35
0.55
0.38
0.4
0.3
0.6
0.39
6x4mm
0.7
0.55
0.5
0.5
0.6
0.8
___
0.6
0.75
0.58
0.65
0.6
0.85
0.64
7x5mm
1.3
1
0.8
1
0.9
1.2
___
1
1.15
1.03
1.25
1.6
1.7
1.15
8x6mm
2.6
1.6
1.4
1.5
1.8
1.7
___
1.7
1.68
1.65
2.4
2.15
2.35
1.8
9x7mm
3.6
2.25
2
3
2.31
2.5
___
2.25
2.3
2.3
3.4
2.8
3.9
2.61
10x8mm
4.2
2.9
3
4
3.15
3.5
___
3.8
2.75
2.95
4
3.6
4.5
3.4
11x9mm
6
4.2
4.3
5
4.5
4.3
___
5.25
4
4.25
5.75
4.3
6.2
4.67
12x10mm
8.5
5.6
4.75
7.8
5.25
6.35
___
6.25
6.25
5.65
8
5.2
7.01
6.19
14x10mm
9.9
7.25
7.75
8.8
5.8
9
___
8.8
9
7.3
9.5
8.5
8.95
8.3
16x12mm
___
13
13.5
13
14
17.5
___
17
12.5
14
14
13
14.3
13.94
18x13mm
___
17
17
20
17.5
21
___
20
18.7
18
21
16.5
19.9
18.69
20x15mm
___
22
22
25.5
22.5
27
___
26
27
24
26
24.9
28.7
25.05
MARQUISE
ALEXANDRITE
AMETHYST
CITRINE
AQUAMARINE
​DIAMOND
EMERALD
GARNET
OPAL
PERIDOT
RUBY SAPPHIRE
​TANZANITE
TOPAZ
TOURMALINE
ZIRCON BLUE
AVERAGE
4x2mm
0.07
0.1
0.08
0.12
0.09
0.09
0.09
0.1
0.13
0.07
0.07
0.1
0.13
0.1
6x3mm
0.3
0.2
0.2
0.25
0.3
0.25
0.17
0.25
0.35
0.23
0.3
0.3
0.33
0.27
8x4mm
0.7
0.5
0.5
0.5
0.6
0.6
0.37
0.5
0.75
0.51
0.7
0.6
0.75
0.6
10x5mm
1.25
0.9
0.8
1
1.1
1.2
0.59
1
1.15
1.25
1.2
0.85
1.25
1.04
12x6mm
2.1
1.59
1.5
2
1.8
2
1
2
2.2
1.63
2
1.55
1.95
1.87
14x7mm
___
2.45
2.75
3
2.8
2.85
1.25
2.55
3
2.5
3.4
2.2
3
2.79
PEAR
ALEXANDRITE
AMETHYST
CITRINE
AQUAMARINE
DIAMOND
​EMERALD
GARNET
OPAL
PERIDOT
RUBY SAPPHIRE
TANZANITE
TOPAZ
TOURMALINE
ZIRCON BLUE
AVERAGE
5x3mm
0.3
0.02
0.2
0.25
0.25
0.25
0.13
0.25
0.3
0.2
0.25
0.35
0.3
0.26
6x4mm
0.5
0.35
0.35
0.5
0.45
0.4
0.22
0.45
0.5
0.4
0.5
0.45
0.7
0.46
7x5mm
0.85
0.65
0.65
0.75
0.7
1
0.35
0.7
0.75
0.75
1
0.6
1
0.77
8x5mm
1.1
0.85
0.9
1
1.05
1.15
0.5
0.8
1
0.9
1.1
0.9
1.3
0.99
9x6mm
2.1
1.28
1.3
1.5
1.7
1.3
0.7
1.1
1.85
1.42
2
1.1
2.6
1.57
10x7mm
3.6
1.7
1.85
2
2.6
1.8
1.03
1.4
2.5
1.78
3.5
1.4
4
2.25
13x8
___
4
4.2
3.5
4.15
3.5
1.4
3.4
4.75
4
6.5
2.8
5.25
4.23
14x10
___
5
5.6
5
6.1
5.8
2.45
4.75
7.9
5.75
8.5
6.75
7.5
6.32
HEART
ALEXANDRITE
AMETHYST
CITRINE
AQUAMARINE
​DIAMOND
EMERALD
GARNET
OPAL
PERIDOT
RUBY SAPPHIRE
TANZANITE
TOPAZ
TOURMALINE
ZIRCON BLUE
AVERAGE
3x3mm
___
0.12
0.09
0.1
0.12
0.16
0.07
0.15
0.15
0.1
0.18
0.1
0.17
0.12
4x4mm
___
0.2
0.21
0.23
0.25
0.3
0.17
0.25
0.36
0.21
0.3
0.25
0.36
0.27
5x5m m
___
0.4
0.39
0.47
0.5
0.5
0.29
0.45
0.6
0.37
0.55
0.4
0.69
0.48
6x6mm
___
0.7
0.61
0.9
0.8
0.85
0.42
0.8
1
0.61
1
0.77
1.25
0.83
7x7mm
___
1.15
1
1.35
___
1.3
0.7
1.3
1.6
1.12
1.6
1.12
1.75
1.31
8x8mm
___
1.54
1.3
1.9
___
1.85
1
2.8
2.25
1.56
2.25
1.58
2.6
1.84
9x9mm
___
2.15
2.2
___
___
2.7
___
___
2.2
3.2
___
2.2
___
2.48
10x10mm
​___
3.05
3
___
___
3.8
1.7
___
3.1
4.3
___
3.1
___
3.44
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