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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Gemstone Information

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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 The only "bad" thing that I have to say is that the interface of the site is outdated.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 -> 8

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

Posted By RayPoppa in January, 2024

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Overall Rating -> 10

Easy to use,I have spent many hours looking at the site

Posted By Skip in November, 2023

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Overall Rating -> 10

It was easy to find the color gem I desired and checkout was simple as well. Very excited to receive my gemstone.

Posted By Nikki J in September, 2023

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Overall Rating -> 10

The website is easy to navigate and has a great selection. I am an amateur silver smith casting jewelry with stones

Posted By Jrplunk in April, 2024

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Overall Rating -> 10

My first order. I am anxious to see if what I ordered is what I receive.

Posted By KRJ in July, 2023

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Overall Rating -> 10

The website is well organized and works fast forward and back. Plenty of filters. Each gem is described in detail and you receive the one pictured. Gem material info and sources available. I would like to see more specifics on sources besides country- at least region or state and in the US with Turquiose which mine. Thanks!

Posted By Orchidisle in February, 2024

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Overall Rating -> 10

I have received emails for about a year and today is the condition that had me decide on the purchase

Posted By Tim in April, 2024

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Overall Rating -> 10

Purchasing from Gem Select was a pleasant and easy experience. The photos of the stones I was interested in were an accurate depiction of the stones I received. Ordering was easy and the items arrived within a week. Over all it was a very positive experience.

Posted By Dee in September, 2023

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Overall Rating -> 10

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

Posted By Jaytee in November, 2023

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Overall Rating -> 10

I love GemSelect, photos and details are great.

Posted By #1 in February, 2024

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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.

Posted By Bob in November, 2023

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Overall Rating -> 9

Well presented images, clear information, quick and easy check out.

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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.

Posted By Ray in February, 2024

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Overall Rating -> 10

Love gemselect

Posted By Joshua Howard in March, 2024

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Gemstones A-Z

Buy Octagon Shape 20x15 mm Gems

1.02 ct Blue Kyanite, 7 x 4.9 mm Oval Cut From Nepal

1.57 carat Orange Hessonite Garnet, Round loose Hessonite Garnet from Madagascar, Natural Untreated Gem, 6.7 mm

1.26 carat Pear Shape Opal, loose Certified Opal from Ethiopia, Natural Untreated Gem, 10.2 x 7.2 mm

0.5 ct Loose Yellow Sapphire, 5 x 4 mm Octagon Cut From Tanzania

3.5 ct Oval Prehnite, 11.5 x 6.9 mm From South Africa

8.38 ct Round Cut Smoky Quartz, 13.7 mm From Brazil

3.08 ct Loose Princess Cut Sapphire, 2.7 x 2.7 mm From Tanzania

46.39 ct Pencil Cut Strawberry Quartz, 37.1 x 12.6 mm From Russia

0.83 carat Yellow Morganite, Pear Shape loose Morganite from Afghanistan, Natural Untreated Gem, 7.8 x 5.9 mm

1.61 carat Green Tourmaline, Round Cabochon loose Tourmaline from Mozambique, Natural Untreated Gem, 7 mm

6.22 ct Oval Tiger's Eye, 14.3 x 10.2 mm From India

16.65 ct Carved Prehnite, 13.7 x 9.7 mm From South Africa

1.45 ct Loose Yellow Sapphire, 6.9 x 5 mm Cushion Cut From Tanzania

1.05 carat Green Tourmaline, Emerald Cut loose Tourmaline from Mozambique, Natural Untreated Gem, 13.8 x 3.6 mm

3.73 carat Pink Tourmaline, Emerald Cut loose Tourmaline from Mozambique, Natural Untreated Gem, 10.1 x 6.7 mm

6.2 carat Pear Pietersite, loose Certified Pietersite from Namibia, Natural Untreated Gems, 14 x 8.5 mm

2.09 ct Oval Cat's Eye Opal, 9.6 x 6.3 mm From Madagascar

3.6 ct Loose Oval Star Ruby, 9.8 x 8 mm From Madagascar

0.18 ct Octagon Cut Iolite, 4.9 x 2.9 mm From Madagascar

9.7 ct Loose Oval Lapis Lazuli, 14.9 x 11 mm From Afghanistan

0.7 carat Pink Morganite, Pear Shape loose Morganite from Afghanistan, Natural Untreated Gem, 8.7 x 4.7 mm

6.89 carat Sky Blue Topaz, Oval loose Topaz from Brazil, Natural Gems, 10.1 x 8.2 mm

0.9 carat Pear Shape Color-Change Diaspore, loose Certified Color-Change Diaspore from Turkey, Natural Untreated Gem, 9.8 x 4.4 mm

0.55 ct Purple Spinel, 6.4 x 3.7 mm Octagon Cut From Tanzania

1.71 carat Red Spessartite Garnet, Round loose Spessartite Garnet from Mozambique, Natural Untreated Gems, 4.2 mm

2.1 carat Sky Blue Topaz, Princess-Cut loose Topaz from Brazil, Natural Gem, 7.1 x 7.1 mm

18.83 carat Bi-color Ametrine, Oval loose Ametrine from Brazil, Natural Untreated Gem, 22 x 13.9 mm

9.88 ct Oval Quartz With Marcasite, 16.1 x 12.4 mm From Brazil

13.48 carat Swiss Blue Topaz, Carved Fruit loose Topaz from Brazil, Natural Gem, 19.8 x 11.2 mm

23.8 ct Oval Fossil Coral, 20 x 13.4 mm From Indonesia

1.26 carat Pink Tourmaline, Emerald Cut loose Tourmaline from Mozambique, Natural Untreated Gem, 9.4 x 4.2 mm

1.83 carat Oval Opal, loose Certified Opal from Ethiopia, Natural Untreated Gems, 7.1 x 5.1 mm

Gemstone Information

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Gemstone EDUCATION

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