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Gemtype Color Shape Weight Size Clarity Price Origin
You Selected (86): Marquise Shape 18x9 mm Gems Clear All
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4 pcs
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2.8ct Marquise Slice Bi-Color Ruby in Fuchsite Gem (ID: 386583)
2.82 ct (total 11.26ctw) Ruby in Fuchsite
17.6 x 9.1 mm
$ 75.89
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1 pc
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3.9ct Marquise Slice Bi-Color Ruby in Fuchsite Gem (ID: 386506)
3.90 ct Ruby in Fuchsite
17.9 x 9.3 mm
$ 26.29
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1 pc
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8.1ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 491265)
8.12 ct Amazonite
18.3 x 9.3 mm
$ 18.11
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1 pc
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6.8ct Marquise Cabochon Green Serpentine Gem (ID: 469592)
6.84 ct Serpentine
18.3 x 9.3 mm
$ 14.36
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1 pc
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4.2ct Marquise Slice Bi-Color Ruby in Fuchsite Gem (ID: 386699)
4.24 ct Ruby in Fuchsite
17.7 x 9.2 mm
$ 28.58
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1 pc
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6.8ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 491250)
6.84 ct Amazonite
18.3 x 9.2 mm
$ 15.25
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1 pc
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7.9ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 491266)
7.90 ct Amazonite
18 x 9.1 mm
$ 17.62
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1 pc
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7.2ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 492128)
7.19 ct Amazonite
17.9 x 9.3 mm
$ 15.75
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2 pcs
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6.2ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 491726)
6.20 ct (total 12.39ctw) Amazonite
18.1 x 9.3 mm
$ 27.51
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2 pcs
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6.3ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 491793)
6.29 ct (total 12.58ctw) Amazonite
17.9 x 9.2 mm
$ 27.93
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1 pc
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4.8ct Marquise Slice Bi-Color Ruby in Fuchsite Gem (ID: 386696)
4.77 ct Ruby in Fuchsite
18.6 x 8.9 mm
$ 32.15
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1 pc
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4.5ct Marquise Slice Bi-Color Ruby in Fuchsite Gem (ID: 386509)
4.54 ct Ruby in Fuchsite
18.7 x 9 mm
$ 30.60
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1 pc
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4.8ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 491251)
4.76 ct Amazonite
18.3 x 9.3 mm
$ 10.61
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1 pc
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6.9ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 492116)
6.92 ct Amazonite
17.6 x 9.2 mm
$ 15.15
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1 pc
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5.1ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 492120)
5.05 ct Amazonite
17.7 x 9 mm
$ 11.06
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1 pc
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6.5ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 491178)
6.50 ct Amazonite
18.1 x 9.3 mm
$ 14.50
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1 pc
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6.8ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 492455)
6.80 ct Amazonite
17.5 x 8.9 mm
$ 14.89
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1 pc
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5.2ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 492130)
5.20 ct Amazonite
18.2 x 9.3 mm
$ 11.39
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1 pc
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7.1ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 491264)
7.10 ct Amazonite
18 x 9.3 mm
$ 15.83
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1 pc
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5.3ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 491256)
5.31 ct Amazonite
18.2 x 9.2 mm
$ 11.84
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1 pc
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5.5ct Marquise Cabochon Blue-Green Amazonite Gem (ID: 492124)
5.49 ct Amazonite
18 x 9.1 mm
$ 12.02
Item in Stock
1 2 3 4
Marquise Shape 18x9 mm Gems
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 18 mm x 9 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.

Certified Customer Reviews
Overall Rating -> 10 star ratings
This was my second purchase from GemSelect and definitely won’t be my last! They have a very wide variety of gems and you can always find what you are looking for with ease and the prices are very good.
Posted By Jill in November, 2018
Source: Bizrate
Overall Rating -> 10 star ratings
Loved the wide selection of product
Posted By Miki in November, 2018
Source: Bizrate
Overall Rating -> 10 star ratings
finally bought the last rock to complete my ring idea; needed another white one after giving the big diamond to my daughter. a diamond that size is out of my retired-school-teacher budget, so i bought a white zircon. went back to the same place that i got my loose sapphire-- great selection, good prices, good delivery!
Posted By Ptcmom in November, 2018
Source: Bizrate
Overall Rating -> 10 star ratings
I'm always real pleased with this website, I don't think there is much you could do to make it any better. I wish the shipping charges were lower, but it is understandable.
Posted By Spinch13 in November, 2018
Source: Bizrate
Overall Rating -> 10 star ratings
This is a site that sources valuable and genuine stones forms around the world, with and honest and descriptive sections, as well as specs, and the option to have the gemstone collection one might purchased—certified! Price ranges vary, but are always affordable and always worth it, whether it’s a gift, or for a personal business.
Posted By Bradley in November, 2018
Source: Bizrate
Overall Rating -> 10 star ratings
I am bored and shopping , it was fun
Posted By Nanorex in November, 2018
Source: Bizrate
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International:
+66-39303404

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Size and Weight

Gems are always measured in Millimeter (mm)

Dimensions are given as;
length x width x depth,
except for round stones which are;
diameter x depth

Select gems by size, not by weight!
Gem varieties vary in density, so carat weight is not a good indication of size

Note: 1ct = 0.2g

Size Comparison Chart