Calibrated Marquise Cut Gemstones in Size 12x6 mm

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 marquise shaped facet cut gems, gemstone carvings and cabochons available in 12 mm x 6 mm sizes. For the largest selection of colored gemstones, Shop GemSelect Online.

As a general guideline, when it comes to calibrated gems, they are not usually expected to be cut to exact measurements and specifications. But rather, they're cut with slight variance in size, though the close approximatation in size is not clearly defined, there are general guidelines for what is considered acceptable. Obviously larger and heavy carat weight stones allow more room in size for variance, while smaller stones may leave little to none. This means a large 30mm calibrated gemstone, could actually be closer to 31 millimeters. For this reason, we recommend to always view the exact size in addition to the calibrated size details. The exact size will inform you of the variance you can expect. Some setting styles are more flexible with variance, such as prong settings, while other styles of mountings may need almost an exact size to the fraction of millimeter.

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 -> 10

Wonderful selection of gems to choose from. Have made many purchases and was only slightly disappointed once.

Posted By Teemo in February, 2024

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Overall Rating -> 10

Super easy to do business for great products.

Posted By BoBBy in January, 2024

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Overall Rating -> 10

blessed be the lord blessed be the saved blessed be the work blessed be the traveled i write down my good times in these stones and when times are gray i can still se the sunny days refract in these stones

Posted By Kickbass.2 in May, 2023

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Overall Rating -> 8

purchased birthstones to be mounted into stud earrings as a gift for a friend's gift

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Overall Rating -> 10

Very Good

Posted By Julian in July, 2023

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Overall Rating -> 10

Great experience! First time buyer

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I have used gm select a while ago and was always pleased with the products

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Overall Rating -> 8

I am currently pleased. I like the layout of the website.

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Overall Rating -> 10

Trustworthy site. I've had several good experiences with company. Products always have met my expectations. Thank you.

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Overall Rating -> 10

The website is very easy to use. The search function, filter and sort functions are very helpful.

Posted By Sboro in August, 2023

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Overall Rating -> 10

I have actually done business with them before and was quite satisfied with them then.My Mother collected turtle items and when I saw the Mother of Pearl turtle...I just thought of her and decided to buy it. It's even tinier than I thought, but so adorable!The gemstones I bought are for jewelry for my daughter's birthday.

Posted By Ktreva52 in February, 2024

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Overall Rating -> 10

Todo muy bien en la compra ahora esperar recibir el pedido.

Posted By MAGSMX in August, 2023

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Overall Rating -> 10

Very pleased with shopping on this site. It's easy to navigate and information about gemstones is very good.

Posted By Kate in December, 2023

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Overall Rating -> 7

I placed order#384714 based on the picture on your website and the stone came in much darker. I'm sure it's the same stone i ordered but your lighting made it seem a lighter blue. I was trying to match a stone for a customer and based on the picture it would have been close enough but the stone in person is a mile off.

Posted By Bobk in February, 2024

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Overall Rating -> 10

Extremely easy to use, and I am fully satisfied with the purchase process.

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Gemstones A-Z

Buy Marquise Shape 12x6 mm Gems

3.73 ct Oval Rutile Quartz, 12 x 8 mm From India

1.68 carat Yellow Citrine, Emerald Cut loose Citrine from Brazil, Natural Untreated Gem, 8.1 x 6.1 mm

0.67 carat Pear Shape Peridot, loose Certified Peridot from China, Natural Untreated Gem, 6.8 x 4.8 mm

0.67 ct Loose Orange Sapphire, 5.5 x 3.9 mm Oval Cut From Tanzania

2 carat Pink Tourmaline, Emerald Cut loose Tourmaline from Tanzania, Natural Untreated Gem, 9.4 x 5.7 mm

1.86 carat Pink Tourmaline, Emerald Cut loose Tourmaline from Mozambique, Natural Untreated Gem, 7.7 x 5.6 mm

13.8 carat Oval Amethyst, loose Certified Amethyst from Brazil, Natural Untreated Gems, 14 x 9.9 mm

12.31 ct Pink Kunzite, 12.8 x 12.6 mm Octagon Cut From Afghanistan

4.75 ct Oval Quartz Cat's Eye, 11.6 x 9.2 mm From Sri Lanka

3.21 carat Sky Blue Topaz, Pear Shape loose Topaz from Brazil, Natural Gems, 6.9 x 5 mm

1.86 carat Yellow Citrine, Trillion loose Citrine from Brazil, Natural Untreated Gem, 8.2 x 9 mm

6.71 ct Pink Kunzite, 10.7 x 9.7 mm Octagon Cut From Afghanistan

2.94 carat Blue Tanzanite, Oval loose Tanzanite from Tanzania, Natural Gem, 9.9 x 8 mm

16.79 ct Oval Rainbow Moonstone, 18.7 x 14.1 mm From the United States

0.71 carat London Blue Topaz, Square loose Topaz from Brazil, Natural Gem, 4.8 x 4.7 mm

1.92 ct Loose Princess Cut Sapphire, 2.3 x 2.3 mm From Tanzania

1.72 carat Orange Zircon, Diamond-Cut loose Zircon from Cambodia, Natural Untreated Gem, 6.7 mm

3.5 carat Sky Blue Topaz, Pear Shape loose Topaz from Brazil, Natural Gems, 6 x 4.3 mm

15.86 carat Pear Jasper, loose Certified Jasper from Indonesia, Natural Untreated Gems, 20.9 x 12 mm

1.41 carat Green Tourmaline, Emerald Cut loose Tourmaline from Mozambique, Natural Untreated Gem, 13 x 3.7 mm

3.21 ct Oval Tiger's Eye, 8.9 x 6.8 mm From Thailand

2.68 carat Square Pyrope Garnet, loose Certified Pyrope Garnet from Mozambique, Natural Untreated Gems, 4 x 4 mm

3.7 carat Pear Shape Amethyst, loose Certified Amethyst from Brazil, Natural Untreated Gem, 13.1 x 9.1 mm

0.47 carat Blue Tanzanite, Pear Shape loose Tanzanite from Tanzania, Natural Gem, 6.1 x 4 mm

0.73 ct Loose Pink Sapphire, 6.2 x 5 mm Oval Cut From Madagascar

17.54 ct Loose Cushion Cut Amethyst, 20.1 x 15.2 mm From Brazil

8.3 ct Fancy Fire Agate, 14.8 x 11.5 mm From Mexico

0.93 carat Pear Shape Peridot, loose Certified Peridot from China, Natural Untreated Gems, 6.1 x 4.1 mm

1.39 carat Oval Ruby, loose Certified Ruby from Madagascar, Natural Gem, 7 x 5.2 mm

11.38 ct Yellow Quartz, 16.1 mm Round Concave Cut From Brazil

2.94 carat Yellow Citrine, Oval loose Citrine from Brazil, Natural Untreated Gem, 10.8 x 8.7 mm

4.24 carat Sky Blue Topaz, Pear Shape loose Topaz from Brazil, Natural Gems, 7 x 5 mm

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