Buy 12 mm Round Calibrated Gemstones from 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 Round shapes, facet cut and cabochon gems available now in 12 mm diameter 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 around 0.3 mm or slightly higher even. This small variance can usually be accommodated for 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

Excellent experience!

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Overall Rating -> 10

Always an easy experience using Gem select.

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Overall Rating -> 10

Super easy to do business for great products.

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Overall Rating -> 10

Great selection and excellent website.

Posted By JBW in October, 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 -> 10

Very excited and impressed with all your products. Keep up the good work....more different stones to choose from. I like Cabachons.

Posted By Meow in June, 2023

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Overall Rating -> 10

I really enjoy browsing through GemSelect. The selection is always marvelous and I love how detailed everything is described. The only thing I noticed is that when browsing through my phone, the videos of the gems do not load. If there were more videos of the gems, that would be amazing, though I understand that is a lot of work on GemSelect's part! Checking out is also very fast and easy, and I love that the return policy is very good, though I hope I don't have to use it anytime soon.

Posted By ChiChi in January, 2024

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Overall Rating -> 10

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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It went well

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Overall Rating -> 9

Never bought anything on this website before, but it probably won't be my last purchase. Definitely one of the easiest to use and most informative sites I've ever been to.

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Overall Rating -> 9

Good interaction with site

Posted By Brick in September, 2023

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Overall Rating -> 10

The website is user friendly, has excellent selection. I've always found what I was looking for with Gem Select. When others don't have it they do. And most important, they have a way for you to pay without using PayPal. I cannot use PayPal they closed my account because of no cell phone.

Posted By NJD in September, 2023

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Overall Rating -> 10

Very large selection of items and we used the stones to have several pieces of jewelry made for us.

Posted By Joe in January, 2024

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Overall Rating -> 10

Easy to find products I want. I've ordered several times from gem select and never any problems. Will order again. Thank you.

Posted By Ray in January, 2024

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Overall Rating -> 10

I love GemSelect, photos and details are great.

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Gemstones A-Z

Buy Round Shape 12 mm Gems

9.38 ct Octagon Cut Smoky Quartz, 12.5 x 12.5 mm From Brazil

2.78 carat Trillion Amethyst, loose Certified Amethyst from Brazil, Natural Untreated Gem, 10 x 9.7 mm

4.6 ct Oval Fire Agate, 12.9 x 10.3 mm From Mexico

22.68 ct Oval Fossil Coral, 18.7 x 12.9 mm From Indonesia

1.06 ct Blue Kyanite, 7.1 x 5 mm Oval Cut From Nepal

0.96 carat Orange Hessonite Garnet, Cushion loose Hessonite Garnet from Sri Lanka, Natural Untreated Gem, 5.3 x 5.3 mm

2.86 carat Blue Tanzanite, Oval loose Tanzanite from Tanzania, Natural Gem, 9.1 x 7.2 mm

19.76 ct Pencil Cut Jasper, 30.8 x 9.2 mm From India

2.77 carat Oval Ruby, loose Certified Ruby from Madagascar, Natural Gems, 7.1 x 5.2 mm

0.46 carat Blue Kyanite, Round loose Kyanite from Nepal, Natural Untreated Gem, 4.3 mm

1.4 carat Yellow Citrine, Oval loose Citrine from Brazil, Natural Untreated Gem, 8.9 x 7 mm

0.52 carat Orange Spessartite Garnet, Round loose Spessartite Garnet from Mozambique, Natural Untreated Gem, 4.5 mm

0.33 ct Loose Yellow Sapphire, 4.1 mm Round Cut From Tanzania

1.51 carat Square Pyrope Garnet, loose Certified Pyrope Garnet from Mozambique, Natural Untreated Gems, 5 x 5 mm

1.87 carat White Zircon, Diamond-Cut loose Zircon from Cambodia, Natural Gems, 5.5 mm

64.04 ct Oval Jasper, 40.9 x 27.2 mm From Indonesia

1.54 ct Oval Cut Black Opal, 11.7 x 8.3 mm From Ethiopia

3.64 carat Orange Zircon, Diamond-Cut loose Zircon from Cambodia, Natural Untreated Gems, 7 mm

1.34 ct Oval Carnelian, 8.1 x 6.2 mm From India

2.65 ct Round Cut Peridot, 4.8 mm From China

0.95 carat Round Cabochon Emerald, loose Certified Emerald from Colombia, Natural Gem, 5.9 mm

7.44 ct Oval Quartz Cat's Eye, 12.1 x 10.6 mm From Sri Lanka

5.25 ct Loose Baguette Labradorite, 8.9 x 6.9 mm From Madagascar

2.6 ct Loose Trillion Cut Amethyst, 10 x 9.8 mm From Brazil

4.18 ct Round Labradorite, 10 mm From Madagascar

1.93 carat Orange Spessartite Garnet, Round loose Spessartite Garnet from Mozambique, Natural Untreated Gems, 4.5 mm

2.02 carat Orange Hessonite Garnet, Cushion loose Hessonite Garnet from Sri Lanka, Natural Untreated Gem, 7.1 x 7.1 mm

7.88 ct Green Amazonite, 7.3 x 7.1 mm Cushion Cut From Madagascar

19.79 carat Emerald Cut Amethyst, loose Certified Amethyst from Brazil, Natural Untreated Gem, 18.1 x 14.2 mm

32.87 ct Yellow Star Sapphire, 21.4 x 18.5 mm Oval Cut From Madagascar

2.19 carat Pear Shape Mystic Quartz, loose Certified Mystic Quartz from Brazil, Natural Gems, 8.1 x 6 mm

0.43 carat Orange Spessartite Garnet, Pear Shape loose Spessartite Garnet from Mozambique, Natural Untreated Gem, 4.8 x 3.9 mm

Gemstone Information

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