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Natural Opal

Opal is a poorly crystalline or amorphous hydrous silica that is compact and vitreous and most commonly translucent white to colourless. Precious opal reflects light with a play of brilliant colours across the visible spectrum, red being the most valued. Opal forms by precipitation from silica-bearing solutions near the Earth's surface. Electron microscopy has shown that many opals are composed of spheres of tens to a few thousand angstroms in size that are arranged in either hexagonal or cubic close packing. The spheres are composed of hydrous silica that may be either almost cristobalite-like, tridymite-like, mixtures of both, or random and nondiffracting. The specific gravity and refractive index are lower than those of pure silica minerals. The play of colours in precious opal arises from the diffraction of light from submicroscopic layers of regularly oriented silica spheres. When heated, opal may lose as much as 20 percent of its weight of water, fracture, and then crystallize to one of the silica minerals described above.

  • There are 36 Opal gemstones available at
  • Opal(s) are organized in the following categories: CloseoutSingle,  gemstones.
  • Our most expensive Opal is USD 1402.20 and largest Opal weight is CTS 58.36.
  • Our cheapest Opal is USD 54.34 and smallest Opal weight is CTS 2.83.

Find your Opal

Our Opal(s) are available in various shapes, sizes and colors. 36 Opal(s), too many to look through? You may select any combination of search options. Colors grade into each other and you can search for more than one color at once. For a better selection, try selecting two or three colors, -- your first choice plus the two closest colors.

Shape Length (mm) Width (mm)
Category Weight (cts) Price (USD)
Color range
orangy yellow

Opal Profile

Color information: White, green, blue, black, red, orange, violet, pink, grey, yellow.
Refractive Index: 1.44-1.46
Chemical Composition: SIO2nH2O
Hardness: 5.5 - 6.0
Density: 2.65 - 3.00
Crystal Group: Amorphous
Ocurrence: Czechoslovakia, Mexico, Honduras, Australia, Brazil, Tanzania.
Sign of the Zodiac: N/A
Month of the year: N/A
Opal usually contains 4 to 9 percent water, but lower and much higher values have been observed. The contents of alumina, ferric oxide, and alkalis are variable but may amount to several percent in light-coloured opals and more if pigmenting minerals are also present. Precious opal has been synthesized. Opaline silica is a friable hydrous silica found near hot springs and geysers.

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Finest gems/
Tourmaline Single
From our finest gemstones collection
Tourmaline Single Oval Slightly included
Size: 14.30 X 10.40 MM
Weight: 6.840 CTS
Shape: Oval
Clarity: Slightly included
Usually ships within 24 hours
USD 87552.00

Deal of the Day/
Beryl Single
limited time offer, ref# ZBE100js
Beryl Single Oval Slightly included
Size: 6.00 X 4.50 MM
Weight: 0.590 CTS
Shape: Oval
Clarity: Slightly included
Usually ships within 24 hours
10 % OFF, YOU SAVE 2.36 USD
USD 21.24

Today’s Trade/
Best Selling Gems:
Sapphire Sapphire
1419 Sapphire ’s available
Browse gems | Learn More
Spinel Spinel
416 Spinel ’s available
Browse gems | Learn More
Tanzanite Tanzanite
457 Tanzanite ’s available
Browse gems | Learn More
Alexandrite Alexandrite
255 Alexandrite ’s available
Browse gems | Learn More
Zircon Zircon
226 Zircon ’s available
Browse gems | Learn More
Gemstone Variety: Hits Index
Going Down Amber -7071 -1.1%
average price USD 194.57 per item
Going Down Sapphire -7733 -1.3%
average price USD 338.57 per item
Going Down Alexandrite -200 -0.1%
average price USD 1552.21 per item
Going Up Tanzanite +131 +0.1%
average price USD 524.86 per item
Going Down Spinel -45 +-0.0%
average price USD 500.21 per item
See more real time gem reports.
Exchange rates to USD
Canada Dollars 1.275
Euro 0.886
United Kingdom Pounds 0.749
Japan Yen 114.091
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Gem Library /
Gems Legend and  Lore This month birthstone: Citrine, Topaz
More from the Gem Library about Birthstones.
Sagittarus Sagittarius
November 22 – December 21
Mutable Sign. Goes at a great gallop. Your zodiac stone...more

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