​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