OPAL

• Chemistry: SiO₂ - nH₂O; Hydrated Silicon Dioxide.
• Class: Mineraloids
• Group: Some minerologists place Opal in the Quartz Group.
• Uses: As a gemstone and ornamental stone.
• The Physical Properties of Opal
• For natural opal mineral specimens see our For Sale or Sold lists

  For Opal Jewelry, see -->

  OPAL JEWELRY

Although there is no crystal structure, (meaning a regular arrangement of atoms) opal does possess a structure nonetheless. Random chains of silicon and oxygen are packed into extraordinarily tiny spheres. These spheres in most Opals are irregular in size and inconsistent in concentration. Yet in Precious Opal, the variety used most often in jewelry, there are many organized pockets of the spheres. These pockets contain spheres of approximately equal size and have a regular concentration, or structure, of the spheres. This has the effect of diffracting light at various wavelengths, creating colors. Each pocket produces a different color and with a different intensity, depending on the angle from which a viewer sees it. The multicolored flashes of light that Opal emits gives it a truly beautiful and valuable look. This effect is called a "play of light", and not "opalescence". The latter term describes the milky nature of the translucence of opal, and is more properly compared to the appearance of water to which a few drops of milk have been added.

The name opal probably is derived from the Sanskrit name for precious stone; upala. It has been mined for centuries, at least since Roman times when they extracted the opal from areas now within the Czech Republic. The Aztecs made use of local Mexican sources as did the Spaniards when they exported the material back to Europe. Today most precious opal comes from Australia with significant sources from Mexico and the Western United States.

Not all opal is so precious however. Common opal lacks opalescence, color or luster and is . . . after all . . . common. Opal is often imitated, forged and "enhanced". Fluorescence, while somewhat unreliable is a good method to determine authenticity.

Opal is the modern Birthstone for October.

PHYSICAL CHARACTERISTICS:

• Color is white, colorless, pale yellow, pale red, gray or black when impurities are common. Diffraction can cause flashes of any color of the rainbow (play of light).
• Luster is vitreous to pearly.
• Transparency: Specimens are transparent to translucent (opalescent).
• Crystal System: Does not apply because opal is amorphous.
• Habits include massive, cavity-fillings such as in fractures and geodes, nodular, reniform or as a replacement of other minerals and wood.
• Cleavage is absent.
• Fracture is conchoidal.
• Hardness is 5.5 - 6
• Specific Gravity is approximately 2 - 2.5 (light)
• Streak is white.
• Other Characteristics: Most specimens will fluoresce white or pale green, some phosphoresce and all specimens can be very sensitive to impacts and low temperatures.
• Associated rocks are chert (a form of microcrystalline quartz), volcanic rocks and many others.
• Notable Occurrences include many Western USA localities; Mexico; Australia; England; Czech Republic and many other localities around the world.
• Best Field Indicators are color play & opalescence, low density, fluorescence, fracture filling tendency and lack of cleavage or crystal faces.

Amethyst Galleries sells natural opal specimens. For Fine Jewelry, see our affiliates:

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Opal Jewelry - Hover over an item for more information

.64 CT TW Citrine and Opal Ring in 14k Gold over Sterling Silver, Size 6,7,8,9 by PalmBeach Jewelry, Size 6,7,8,9
Rated by 25,000+ Customers. .64 CT TW Citrine and Opal Ring in 14k Gold over Sterling SilverOnly $79.99 at

.64 CT TW Citrine and Opal Ring in 14k Gold over Sterling Silver, Size 6,7,8,9 by PalmBeach Jewelry, Size 6,7,8,9
$79.99

Australian Opal Ring with Tanzanite
Metal:˙Silver .925Size:˙All sizes are available. If not we resize them for free of charge.Metal Finish:˙RhodiumStone/s:˙Australian Opal + Tanzanite + CZ˙This item usually arrives in 2-3 business days. Arrival date depends on the item selected.Shipping...Only $181.74 at

Australian Opal Ring with Tanzanite
$181.74

Lab-Created Opal & White Sapphire Band at JCPenney
Simple, yet exquisite, this sterling silver band features an alternating row of sparkling white sapphires and lustrous opal stones. Metal: Sterling silver Metal Color: White Stones: .44 ctw. lab-created white sapphires, 2.8mm Other Stones: lab-created...Only $50.00 at

Lab-Created Opal & White Sapphire Band at JCPenney
$50.00

Opal Ring with Diamonds 2.00 Carat (ctw) in Sterling Silver, Size 10
Opal Ring with Diamonds 2.00 Carat (ctw) in Sterling Silver, Size 10 #68CK8502OP:V10. This 2.0 carat (ctw) opal and diamond ring is crafted from white polished sterling silver curving gracefully around and behind the seven stones. Six round, brilliant...Only $99.00 at

Opal Ring with Diamonds 2.00 Carat (ctw) in Sterling Silver, Size 10
$99.00

Oval Opal and Diamond Designer Earrings Studs in Sterling Silver
AAA opals accented by diamonds are for the trendsetter. One of our best sellers, this design is truly unique.Only $109.99 at

Oval Opal and Diamond Designer Earrings Studs in Sterling Silver
$109.99

Oval Cut Mexican Fire Cherry Opal Silver Ring .925
Oval Cut Mexican Fire Cherry Opal Silver Ring .925 with approximately 2 carat fire cherry opal made with .925 sterling silver and a rhodium finish to give it a white gold look.Metal:˙Silver .925Size:˙All sizes are available. If not we resize them for...Only $176.80 at

Oval Cut Mexican Fire Cherry Opal Silver Ring .925
$176.80

Sterling Silver Rainbow Fire Solid Australian Crystal Opal Ring Jewelry
This Ring was handmade by a master artisan and is one of a kind.Only $182.24 at

Sterling Silver Rainbow Fire Solid Australian Crystal Opal Ring Jewelry
$182.24

Opal and Tanzanite Heart Silver Pendant
Metal:˙Silver .925Dimensions:˙3.5 cms (1.38"") no chain included.\nMetal Finish:˙Rhodium / PolishedStone/s:˙Australian Opal + TanzaniteBrand:˙Silver Best Buy Co.\n˙Shipping Information:\nThis item usually arrives in 2-3 business days. Arrival date...Only $116.74 at

Opal and Tanzanite Heart Silver Pendant
$116.74

Written in the Stars Ring Round Peridot Sterling Silver Ring with Fire Opal
Two glittering gemstones and numerous star etchings rest atop the hollowed upper band of this gleaming ring, designed for the stargazers among us.Only $155.00 at

Written in the Stars Ring Round Peridot Sterling Silver Ring with Fire Opal
$155.00

Lab-Created Opal & Genuine Topaz Earrings at JCPenney
appraised at learn more about appraisals Trillion-cut lab-created opals take center stage in these unique sterling silver earrings, emanating an everchanging play of fantasy colors backed by swirls of white topaz. Metal: Sterling silver Metal Color:...Only $50.00 at

Lab-Created Opal & Genuine Topaz Earrings at JCPenney
$50.00

Lab-Created Pink Opal & Diamond-Accent Pendant at JCPenney
Make your style statement with this bold and beautiful opal pendant. The vintage-inspired design features a large, oval-shaped pink opal set off by sparkling diamond accents set around the center stone and sterling silver bail. Metal: Sterling silver...Only $100.00 at

Lab-Created Pink Opal & Diamond-Accent Pendant at JCPenney
$100.00

Opal Ring with Diamonds 2.00 Carat (ctw) in Sterling Silver, Size 7.5
Opal Ring with Diamonds 2.00 Carat (ctw) in Sterling Silver, Size 7.5 #68CK8502OP:V7.5. This 2.0 carat (ctw) opal and diamond ring is crafted from white polished sterling silver curving gracefully around and behind the seven stones. Six round,...Only $99.00 at

Opal Ring with Diamonds 2.00 Carat (ctw) in Sterling Silver, Size 7.5
$99.00

Australian Opal Ring with Tanzanite
Metal:˙Silver .925Size:˙All sizes are available. If not we resize them for free of charge.Metal Finish:˙RhodiumStone/s:˙Australian Opal + Tanzanite + CZ˙This item usually arrives in 2-3 business days. Arrival date depends on the item selected.Shipping...Only $153.40 at

Australian Opal Ring with Tanzanite
$153.40

Opal Ring with Diamonds 2.00 Carat (ctw) in Sterling Silver, Size 6.5
Opal Ring with Diamonds 2.00 Carat (ctw) in Sterling Silver, Size 6.5 #68CK8502OP:V6.5. This 2.0 carat (ctw) opal and diamond ring is crafted from white polished sterling silver curving gracefully around and behind the seven stones. Six round,...Only $99.00 at

Opal Ring with Diamonds 2.00 Carat (ctw) in Sterling Silver, Size 6.5
$99.00

Modern Flower Ring Round Blue Topaz Sterling Silver Ring with Fire Opal
Six, sparkling petals surround a seventh round-cut stone. The bezel setting gives a stylish, modern feel to a classic, star-shaped flower ring.Only $143.00 at

Modern Flower Ring Round Blue Topaz Sterling Silver Ring with Fire Opal
$143.00

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