Calibrated 20 x 15 mm Octagon Shape Natural Gemstones: GemSelect

Some people by gems by color or price, but for many, it is best to buy gems by shape and size - especially if you're in need of a gem to replace a previous item that was lost or damaged. Calibrated Octagon shape / Emerald-Cut, faceted and cabochon gems available now in 20 x 15 mm size range. Shop a wide range of calibrated gemstones by size online at wholesale from GemSelect.

As a general guideline, when it comes to 'calibrated' gems, they are not usually expected to be cut to exact measurements. For calibrated gemstones weighing under one carat, most jewelry settings will accommodate a gem which is within 0.2 mm of the calibrated size in order to fit a standard setting. For gemstones that weigh over one carat, a larger variance is acceptable, often round shape settings will allow 0.3 mm or slightly higher even. This small variance can usually be accommodated for most standard style settings. Round-cut gemstones should also have a greater variance in acceptable size when it comes to calibration; in fact it is usually possible to mount a round stone of any size in the closest standard setting.

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Overall Rating -> 8

I did not realize how small the stone was. I cannot use it for the project I wanted, but I am keeping the stone and tru to use it in something else.

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Overall Rating -> 10

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Was easy to search for many gems and mineral stones.Authenticity of natural stones is important, and I feel this site offers some assurance on this.

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Overall Rating -> 10

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I searched for the item by description and millimeter and had my choice come up and then made the best selection.

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Gemstones A-Z

Buy Octagon Shape 20x15 mm Gems

2.07 carat Orange Hessonite Garnet, Oval loose Hessonite Garnet from Madagascar, Natural Untreated Gem, 8.7 x 7.2 mm

1.85 carat Blue Zircon, Diamond-Cut loose Zircon from Cambodia, Natural Gems, 4.3 mm

1.45 carat Round Opal, loose Certified Opal from Ethiopia, Natural Untreated Gems, 5.1 mm

2.02 carat Yellow Citrine, Oval loose Citrine from Brazil, Natural Untreated Gem, 9.1 x 7.1 mm

0.83 carat Orange Sunstone, Oval loose Sunstone from India, Natural Untreated Gem, 8.1 x 6.9 mm

8.76 ct Round Rutile Quartz, 14 mm From India

13.24 ct Carved Prehnite, 17.2 x 11.3 mm From South Africa

4.17 ct Oval Tiger's Eye, 14.1 x 10.2 mm From India

0.99 ct Loose Purple Tourmaline, 6.3 mm Round Cabochon From Mozambique

60.57 ct Oval Jasper, 35.2 x 23.3 mm From Indonesia

21.61 carat Oval Opal, loose Certified Opal from Australia, Natural Untreated Gem, 7 x 17.3 mm

1.97 carat Orange Hessonite Garnet, Cushion loose Hessonite Garnet from Madagascar, Natural Untreated Gem, 7.1 x 7 mm

6.09 ct Loose Pear Cut Mystic Quartz, 12.1 x 8.1 mm From Brazil

2.78 carat Blue Zircon, Diamond-Cut loose Zircon from Cambodia, Natural Gems, 4.5 mm

19.54 carat Cushion Amethyst, loose Certified Amethyst from Brazil, Natural Untreated Gem, 18.1 x 18 mm

1.68 carat Oval Ruby, loose Certified Ruby from Madagascar, Natural Gem, 7.9 x 6 mm

1.07 carat Orange Hessonite Garnet, Emerald Cut loose Hessonite Garnet from Madagascar, Natural Untreated Gem, 6.5 x 5.2 mm

0.55 ct Loose Orange Sapphire, 5.9 x 4 mm Oval Cut From Tanzania

0.56 ct Loose Orange Sapphire, 4.4 x 4.4 mm Cushion Cut From Tanzania

2.13 carat Blue Zircon, Diamond-Cut loose Zircon from Cambodia, Natural Gems, 4.5 mm

2.91 carat Heart Pyrope Garnet, loose Certified Pyrope Garnet from Mozambique, Natural Untreated Gems, 5.9 x 5.9 mm

3.85 carat Swiss Blue Topaz, Marquise-Cut loose Topaz from Brazil, Natural Gem, 15 x 7.3 mm

0.95 ct Oval Strawberry Quartz, 7.6 x 5.8 mm From Russia

4.52 ct Oval Rose Cut Smoky Quartz, 9.6 x 7.7 mm From Brazil

0.65 ct Loose Orange Sapphire, 6.1 x 4.2 mm Oval Cut From Tanzania

11.84 ct Round Cut Smoky Quartz, 15.8 mm From Brazil

1.9 carat Blue Tanzanite, Pear Shape loose Tanzanite from Tanzania, Natural Gems, 5 x 3 mm

13.5 ct Green Amazonite, 19.5 x 10.1 mm Marquise Cut From Madagascar

0.53 ct Loose Violet Sapphire, 5.9 x 4 mm Oval Cut From Tanzania

2.78 ct Oval Concave Cut Smoky Quartz, 14.1 x 7.1 mm From Brazil

2.8 carat Square Rhodolite Garnet, loose Certified Rhodolite Garnet from Mozambique, Natural Untreated Gems, 5 x 5 mm

1.38 carat Orange Hessonite Garnet, Square loose Hessonite Garnet from Sri Lanka, Natural Untreated Gems, 3.7 x 3.6 mm

Gemstone Information

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Gemstone EDUCATION

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