Size Charts

ROUND BRILLIANT CUT STONES

Size/Weight Comparison Charts

How to use these charts: Gemstones will vary slightly because of the different densities of the the stone, For example you can see from the first chart that a 6mm round brilliant diamond might weigh 0.90 ct while a 6mm Ruby in an equivalent 6mm size would weigh approximately 1.05 cts. These numbers are estimates only and can vary based on a stones depth, but should still give you a general idea on how density can effect a stones weight.

ROUND BRILLIANT CUT STONES

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GEMSTONE 2mm 3mm 4mm 5mm 6mm 7mm 8mm
Alexandrite .04 .12 .35 .63 1.30 2.15 2.90
Amethyst .04 .10 .20 .40 .70 1.30 1.80
Aquamarine .04 .10 .25 .45 .75 1.60 2.40
Citrine .04 .10 .20 .40 .70 1.30 1.80
Diamond .04 .10 .23 .47 .90 1.35 1.90
Emerald .04 .12 .27 .48 .80 1.70 2.50
Garnet .05 .13 .30 .60 1.00 1.60 2.50
Opal .02 .09 .16 .34 .57 .83 1.30
Peridot .05 .12 .26 .50 .85 1.25 2.00
Ruby .05 .15 .34 .65 1.05 1.60 2.25
Sapphire .05 .15 .34 .65 1.05 1.60 2.25
Topaz .04 .11 .30 .56 1.00 1.55 2.50
Tourmaline .04 .12 .24 .45 .75 1.55 2.00
Zircon .06 .17 .36 .69 1.25 1.75 2.60
OVAL CUT STONES
GEMSTONE 5×3 6×4 7×5 8×6 9×7 10×8 11×9 12×10 14×10 16×12 18×13
Alexandrite .30 .61 .80 1.45 2.00 3.60 4.25 6.00 8.90 12.50 18.00
Amethyst .23 .45 .85 1.25 1.75 2.40 3.20 4.50 6.50 11.00 14.00
Aquamarine .20 .40 .75 1.10 1.75 2.25 3.00 4.50 6.75 10.15 10.57
Citrine .23 .45 .85 1.25 1.75 2.40 3.25 4.20 5.20 9.00 10.75
Diamond .25 .50 .75 1.40 2.00 3.00 4.00 5.00 8.00 11.50 16.00
Emerald .28 .52 .85 1.00 1.60 2.25 3.75 5.00 7.50 12.00 14.50
Garnet .25 .55 1.00 1.40 2.10 2.80 3.75 5.00 7.00 10.00 13.25
Opal .16 .28 .47 .75 1.10 1.65 2.15 3.00 4.00 5.25 5.75
Peridot .28 .50 .95 1.35 2.00 2.50 3.50 4.00 6.00 9.50 13.00
Ruby .35 .60 1.00 1.55 2.20 3.15 3.80 6.00 7.25 12.00 13.00
Sapphire .35 .60 1.00 1.55 2.20 3.15 3.80 6.00 7.25 12.00 13.00
Topaz .27 .57 1.10 1.60 2.50 3.50 4.50 6.00 8.80 12.00 17.00
Tourmaline .25 .50 .90 1.18 2.30 2.90 3.50 5.25 6.80 8.50 12.00
Zircon .40 .75 1.45 2.00 2.85 4.00 5.60 7.50 8.20 13.50 14.50

 

EMERALD CUT STONES
GEMSTONE 5×3 6×4 7×5 8×6 9×7 10×8 11×9 12×10 14×10 16×12 18×13
Alexandrite .40 .70 1.30 2.60 3.60 4.20 6.00 8.50 9.90 14.50 22.00
Amethyst .35 .55 1.00 1.60 2.25 2.90 4.20 5.60 7.25 13.00 17.00
Aquamarine .25 .50 .80 1.40 2.00 3.00 4.30 4.75 7.75 13.50 17.00
Citrine .35 .55 1.00 1.60 2.25 2.90 4.20 5.60 7.25 13.00 17.00
Diamond .25 .50 1.00 1.50 3.00 4.00 5.00 7.8 8.80 13.00 20.00
Emerald .30 .60 .90 1.80 2.31 3.15 4.50 5.25 5.80 14.00 17.50
Garnet .40 .80 1.20 1.70 2.50 3.50 4.30 6.35 9.00 17.50 21.00
Peridot .35 .60 1.00 1.70 2.25 3.80 5.25 6.25 8.80 17.00 20.00
Ruby .55 .75 1.15 1.75 2.30 2.75 4.00 6.25 9.00 12.50 18.70
Sapphire .55 .75 1.15 1.75 2.30 2.75 4.00 6.25 9.00 12.50 18.70
Topaz .40 .65 1.25 2.40 3.40 4.00 5.75 8.00 9.50 14.00 21.00
Tourmaline .30 .60 1.60 2.15 2.80 3.60 4.30 5.20 8.50 13.00 16.50
Zircon .60 .80 1.70 2.35 3.90 4.50 6.20 7.05 8.95 14.30 19.90
PEAR CUT STONES
GEMSTONE 5×3 6×4 7×5 8×5 9×6 10×7 13×8 14×10
Alexandrite .30 .50 .85 1.10 2.10 3.60 6.60 8.80
Amethyst .20 .35 .65 .85 1.25 1.70 4.00 5.00
Aquamarine .20 .35 .65 .90 1.30 1.85 4.20 5.60
Citrine .20 .35 .65 .85 1.30 1.70 4.00 5.00
Diamond .25 .50 .75 1.00 1.50 2.00 3.50 5.00
Emerald .25 .45 .70 1.05 1.70 2.60 4.15 6.10
Garnet .25 .40 1.00 1.15 1.30 1.80 3.50 5.80
Opal .13 .22 .35 .50 .70 1.03 1.40 2.45
Peridot .25 .45 .70 .80 1.10 1.40 3.40 4.75
Ruby .30 .50 .75 1.00 1.85 2.50 4.75 7.90
Sapphire .30 .50 .75 1.00 1.85 2.50 4.75 7.90
Topaz .25 .50 1.00 1.10 2.00 3.50 6.50 8.50
Tourmaline .35 .45 .60 .90 1.10 1.40 2.80 6.75
Zircon .30 .70 1.00 1.30 2.60 4.00 5.25 7.50

 

MARQUISE CUT STONES
GEMSTONE 4×2 6×3 8×4 10×5 12×6 14×7
Alexandrite .07 .30 .70 1.25 2.10 3.50
Amethyst .10 .20 .48 .90 1.59 2.45
Aquamarine .08 .20 .50 .80 1.50 2.75
Citrine .10 .20 .50 .90 1.59 2.45
Diamond .12 .25 .50 1.00 2.00 3.00
Emerald .09 .30 .60 1.10 1.80 2.80
Garnet .09 .25 .60 1.20 2.00 2.85
Opal .09 .17 .37 .59 1.00 1.25
Peridot .10 .25 .50 1.00 2.00 2.55
Ruby .13 .35 .75 1.15 2.20 3.00
Sapphire .13 .35 .75 1.15 2.20 3.00
Topaz .07 .30 .70 1.20 2.00 3.40
Tourmaline .10 .30 .60 .85 1.55 2.20
Zircon .13 .33 .75 1.25 1.95 3.00

 

Physical Properties of Gemstones

Name Hardness Chemical Composition Density
Alexandrite 8.5 BeAl2O4 3.73
Amethyst 7 SiO2 2.66
Ametrine 7 SiO2 2.66
Beryl 7.5 Be3Al2(SiO3)6 2.67-2.745
Chrome
Tourmaline
7-7.5 (NaCa)(LI,MgFe,Al)9B3Si6(O,OH)31 3.06 (.05,
+.15)
Chrysoberyl 8.5 BeAl2O4 3.73
Chrysoberyl Cats
Eye
8.5 BeAl2O4 3.73
Diamond 10 C 3.52
Emerald 7.5-8 Be3Al2(SiO3)6 2.72 (-.05,
+.12)
Kyanite 4.5 – 7.0 AL2SIO5 3.56 –
3.68
Malaia Garnet 7 – 7.5 [Mg3 +
Mn3]AL2(SIO4)
3.65 – 4.20
Mali Garnet 7.25 Ca3Al2(SiO4)3 3.65
Opal 5.5 – 6.0 SIO2nH2O 2.65 – 3.00
Peridot 6.5 (Mg,Fe)2(SiO)4 3.34
Quartz 7 SiO2 2.65
Ruby 9 AL2O3 4
Sapphire 9 AL22O3 4
Spessartite
Garnet
7.25 Mn3Al2(SiO4)3 4.14-4.20
Spinel 8 MgAl2O4 3.60 (-.03,
+.30)
Star Sapphire 9 AL2O3 4
Tanzanite 6-7 Ca2(Al,OH)Al2(SIO4) 3.30 (+.10,
-.10)
Topaz 8 AL(F,OH)2SIO4 3.52 – 3.56
Tourmaline 7-7.5 (NaCa)(LI,MgFe,Al)9B3Si6(O,OH)31 3.06 (.05,
+.15)
Tsavorite 7 Ca3Al2(SiO4)3 3.61(-.27,
+.12)
Turquoise 5.5-6 CuAl6(PO4)4(OH)85H2O 2.60- 2.90
Zircon 7.5 ZrSiO4 4.00-4.73