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LOOSE GEMSTONES

Natural gemstones weight chart

Calibrated Size Charts for Gemstones to be set in Standard Jewelry Mountings

Oval GemstonesOval Cut

Calibrated Size Chart for Standard Jewelry Mountings (approximate weights)

Size in mm
Weight in carat

5×3 6×4 7×5 8×6 9×7 10×8 11×9 12×10 14×12
Alexandrite .30 .51 .80 1.45 2.00 3.60 4.25 6.00 8.90
Amethyst .23 .45 .85 1.25 1.75 2.40 3.20 4.50 6.50
Aquamarine .20 .40 .75 1.10 1.75 2.25 3.00 4.50 6.75
Citrine .23 .45 .85 1.25 1.75 2.40 3.25 4.20 5.20
Diamond .25 .50 .75 1.40 2.00 3.00 4.00 5.00 8.00
Emerald .25 .52 .85 1.26 1.90 2.60 3.75 5.00 7.50
Pyrope Garnet .25 .55 1.00 1.40 2.10 2.80 3.75 5.00 7.00
Iolite .21 .40 .63 1.02
Opal .16 .28 .47 .78 1.10 1.65 2.15 3.00 4.00
Peridot .28 .50 .95 1.35 2.00 2.50 3.50 4.00 6.00
Ruby .35 .60 1.06 1.55 2.20 3.15 3.80 6.00 7.25
Sapphire .35 .60 1.00 1.55 2.20 3.15 3.80 6.00 7.25
Tanzanite .20 .48 .89 1.35
Topaz .28 .57 1.10 1.60 2.50 3.50 4.50 6.00 8.80
Tourmaline .25 .50 .90 1.18 2.30 2.90 3.50 5.25 6.80
Tsavorite .28 .52 .75
Zircon .40 .75 1.45 2.00 2.85 4.00 5.60 7.50 8.20
Round GemstonesRound Cut

Calibrated Size Chart for Standard Jewelry Mountings (approximate weights)

Size in mm
Weight in carat

2 3 4 5 6 6.5 7 8 10
Alexandrite .04 .12 .35 .63 1.30 1.86 2.15 2.90 5.20
Amethyst .04 .10 .20 .40 .70 1.10 1.30 1.80 3.30
Aquamarine .04 .10 .25 .45 .75 1.31 1.60 2.40 3.50
Citrine .04 .10 .20 .40 .70 1.10 1.30 1.80 3.30
Diamond .03 .10 .23 .47 .80 1.00 1.25 1.90 3.50
Emerald .04 .12 .27 .48 .80 1.26 1.70 2.50 6.10
Pyrope Garnet .05 .13 .30 .60 1.00 1.40 1.60 2.50 5.75
Opal .02 .09 .16 .34 .57 .75 .83 1.30 2.00
Peridot .05 .12 .26 .50 .85 1.11 1.25 2.00 5.25
Ruby .05 .15 .34 .65 1.05 1.41 1.60 2.25 4.50
Sapphire .05 .15 .34 .65 1.05 1.41 1.60 2.25 4.50
Topaz .04 .11 .30 .56 1.00 1.36 1.55 2.50 5.75
Tourmaline .04 .12 .24 .45 .75 1.28 1.55 2.00 3.00
Zircon .06 .17 .36 .69 1.25 1.58 1.75 2.60 5.00
Pear GemstonesPear Cut

Calibrated Size Chart for Standard Jewelry Mountings (approximate weights)

Size in mm
Weight in carat

5×3 6×4 7×5 8×6 9×6 10×7 12×8 14×9
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
Pyrope 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
Octagon GemstonesOctagon / Emerald Cut

Calibrated Size Chart for Standard Jewelry Mountings (approximate weights)

Size in mm
Weight in carat

5×3 6×4 7×5 8×6 9×7 10×8 11×9 12×10 14×12
Alexandrite .40 .70 1.30 2.60 3.60 4.20 6.00 8.50 9.90
Amethyst .35 .55 1.10 1.60 2.25 2.90 4.20 5.60 7.25
Aquamarine .25 .50 .80 1.40 2.00 3.00 4.30 4.75 7.75
Citrine .35 .55 1.00 1.60 2.25 2.90 4.20 5.60 7.25
Diamond .25 .50 1.00 1.50 3.00 4.00 5.00 7.80 8.80
Emerald .30 .60 .90 1.80 2.31 3.15 4.50 5.25 5.80
Pyrope Garnet .40 .80 1.20 1.70 2.50 3.50 4.30 6.35 9.00
Peridot .35 .60 1.00 1.70 2.25 3.80 5.25 6.25 8.80
Ruby .55 .75 1.15 1.60 2.30 2.75 4.00 6.25 9.00
Sapphire .55 .75 1.15 1.75 2.30 2.75 4.00 6.25 9.00
Topaz .40 .65 1.25 2.40 3.40 4.00 5.75 8.00 9.50
Tourmaline .30 .60 1.60 2.15 2.80 3.60 4.30 5.20 8.50
Zircon .60 .85 1.70 2.35 3.90 450 6.20 7.01 8.95
Marquise GemstonesMarquise Cut

Calibrated Size Chart for Standard Jewelry Mountings (approximate weights)

Size in mm
Weight in carat

4×2 5×3 6×3 7×3.5 8×4 10×5 12×6 14×7
Alexandrite .07 .20 .30 .50 .70 1.25 2.10 3.50
Amethyst .10 .15 .20 .34 .48 .90 1.59 2.45
Aquamarine .08 .14 .20 .25 .50 .80 1.50 2.75
Citrine .10 .15 .20 .35 .50 .90 1.59 2.45
Diamond .12 .18 .25 .37 .50 1.00 2.00 3.00
Emerald .09 .19 .30 .45 .60 1.40 1.80 2.80
Pyrope Garnet .09 .16 .25 .42 .60 1.20 2.00 2.85
Opal .09 .13 .17 .27 .37 .59 1.00 1.25
Peridot .10 .17 .25 .37 .50 1.00 2.00 2.55
Ruby .13 .24 .35 .55 .75 1.15 2.20 3.00
Sapphire .13 .24 .35 .55 .75 1.15 2.20 3.00
Topaz .07 .17 .30 .50 .70 1.20 2.00 3.40
Tourmaline .10 .20 .30 .45 .60 .85 1.55 2.20
Zircon .13 .23 .33 .55 .75 1.25 1.95 3.00