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

Very easy. I have purchased a few times before and was satisfied each time. Thank you.

Posted By Ray in December, 2023

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Overall Rating -> 9

My first purchase went well. I will purchase more gems in the future.

Posted By NoHalalAl in March, 2024

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Overall Rating -> 10

Easy to navigate

Posted By G Funk in December, 2023

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Overall Rating -> 10

Fantastic dealer for quality gemstones. Website is easy to navigate, selection is superb, delivery of purchases is prompt. Easy to select incorrect payment options, however.

Posted By David W in May, 2023

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Overall Rating -> 9

Everything was good but since I am still new I was surprised at how small the stones where.

Posted By Js in May, 2023

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Overall Rating -> 10

was just windowshopping and spotted a couple "Very Uncommons", a tsavorite & a demantoid garnet that were both in a size I was looking for, & that I could very easily pay for -- so figured I would grab the tsavo ASAP and got the demantoid to accompany so they wouldn't be lonely.

Posted By Kittypie070 in April, 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 -> 9

Overall good, shipping prices just seem a little on the high side.

Posted By Steve in August, 2023

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Overall Rating -> 10

I was looking for ammolite for my husband. Other websites are not always clear about whether they have genuine ammolite or simulated ammolite. I have purchased from GemSelect before and trust that the stones are genuine. Finding the stones I want is easy, and I love all of the search filter options!

Posted By Ana in September, 2023

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Overall Rating -> 8

Very easy to find the specific stone I was looking for. I am pleased by both the selection and the price of the stones that are available. The only "bad" thing that I have to say is that the interface of the site is outdated.

Posted By Nick in March, 2024

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Overall Rating -> 10

I purchase all of my stones from GemSelect! They're the best I've found for both selection and value.

Posted By Terry in June, 2023

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Overall Rating -> 9

Good interaction with site

Posted By Brick in September, 2023

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Overall Rating -> 10

Awesome

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Overall Rating -> 10

No issues at all. It was great.

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Overall Rating -> 10

I particularly like information about product provided with purchase.

Posted By Dick in May, 2023

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Gemstones A-Z

Buy Round Shape 12 mm Gems

2.42 ct Loose Oval Cut Black Opal, 12.8 x 9.5 mm From Ethiopia

1.13 ct Loose Yellow Sapphire, 7 x 5.1 mm Cushion Cut From Tanzania

2.93 carat Trillion Amethyst, loose Certified Amethyst from Brazil, Natural Untreated Gem, 10.1 x 10 mm

0.48 ct Purple Spinel, 4.5 x 4.2 mm Cushion Cut From Tanzania

1.34 ct Oval Smoky Quartz, 8 x 6 mm From Brazil

38.75 ct Trillion Obsidian, 34.9 x 25.8 mm From Mexico

3.55 carat Yellow Citrine, Square loose Citrine from Brazil, Natural Untreated Gem, 8.9 x 8.9 mm

19.5 ct Fancy Howlite, 29 x 14.5 mm From the United States

1.18 carat Brown Tourmaline, Pear Shape loose Tourmaline from Tanzania, Natural Untreated Gem, 8.7 x 6.4 mm

1.15 ct Marquise Cut Peridot, 8.1 x 4 mm From China

1.04 ct Loose Oval Peridot, 6 x 4.2 mm From China

2.6 carat Yellow Citrine, Trillion loose Citrine from Brazil, Natural Untreated Gems, 6.2 x 6.1 mm

0.4 ct Loose Pink Sapphire, 5.2 x 4.1 mm Odd Shaped From Tanzania

3.18 carat Yellow Citrine, Heart loose Citrine from Brazil, Natural Untreated Gems, 6.7 x 6.5 mm

2.16 carat White Zircon, Oval loose Zircon from Cambodia, Natural Gems, 7.1 x 5 mm

4.98 ct Orange Sunstone, 9 mm Round Cut From India

4.97 ct Oval Rutile Quartz, 13 x 9 mm From India

1.29 ct Black Star Sapphire, 7.5 x 5.7 mm Oval Cut From Thailand

16.85 ct Heart Jasper, 19.8 x 13.5 mm From Indonesia

16.39 carat Ammolite, loose Certified Ammolite from Canada, Natural Gem, 20.7 x 14.4 mm

2.54 carat Emerald Cut Pyrope Garnet, loose Certified Pyrope Garnet from Mozambique, Natural Untreated Gems, 6 x 4 mm

6.37 carat Sky Blue Topaz, Heart loose Topaz from Brazil, Natural Gems, 9 x 9 mm

6.62 ct Purple Kunzite, 10.6 x 8.6 mm Octagon Cut From Afghanistan

1.52 carat Yellow Citrine, Heart loose Citrine from Brazil, Natural Untreated Gems, 6.1 x 6.1 mm

6.8 ct Round Pietersite, 11.9 mm From Namibia

1.75 ct Blue Apatite, 5.9 x 4 mm Oval Cut From Madagascar

0.54 ct Orange Sphalerite, 4.5 mm Round Cut From Spain

78.76 ct Oval Jasper, 37.5 x 29.1 mm From Indonesia

7.01 ct Loose Multicolor Mystic Quartz, 10 mm Round Concave Cut From Brazil

13.81 carat Blue Aquamarine, Emerald Cut loose Aquamarine from Madagascar, Natural Untreated Gem, 18.4 x 10.3 mm

4.79 ct Round Rutile Quartz, 11.1 mm From India

0.67 ct Oval Cut Color-Change Diaspore, 6.1 x 5 mm From Brazil

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