Precious opal may seem to contain every color in the rainbow, depending on which angle you look at it. This color-changing phenomenon, known as iridescence or color play, has captivated imaginations for centuries. Thanks to its flashing colors, often resembling the flecks in irises, it has been thought to bring good luck and heal to eye ailments. Other cultures associate it with bad luck and the evil eye. Not surprisingly, perhaps, it’s been employed in Rorschach-type tests in psychology.

Opal, made of hydrated or hardened silica gel, is 5 to 30 percent water, which means the stone may eventually dry out, causing it to lose its iridescence and crack. Iridescence is created by the structure of the stone, wherein tiny, tightly packed silica spheres diffract light. The bigger and more orderly these spheres, the more color the opal appears to contain.

An amorphous stone, opal is formed in the cavities of sedimentary rocks such as ironstone and sandstone. It also creates veins in igneous rocks, is found in stalagmites or stalactites in caves, and works as a petrifying agent, replacing wood, shell, and bones in fossils. Before the 19th century, Czechoslovakia was the primary source of precious opal, but these days it’s Australia. Opal is also mined in Brazil, Ethiopia, Honduras, Indonesia, Japan, Mexico, Peru, Russia, southern Africa, and in Nevada and Idaho in the United States.

Being a soft, fragile stone, opal is easy to damage and difficult to work with. Nonetheless, jewelers find its enchanting color difficult to resist. Opal is often cut into cabochons with free-form shapes that best show off the color play within. These unique shapes inspire much creativity in the jewelry design for necklaces, rings, and bracelets. Opal may be opaque to translucent to transparent. It comes in a wide range of base colors, and generally has a vitreous luster.

There are both precious and non-precious types of opal. Perhaps the most well-known of the precious is called white opal, which has a light-colored based such as white or cream and intense color play. These opals may appear washed out without a closed-back bezel setting, which bring out their iridescence.

Even more rare and desirable, though, is black opal, which has a higher carat price than white. Black opal is actually a dark-colored opal, which can be gray, blue, green, or gray-black. Less dark is the precious jelly or semiblack opal, which has a lighter base in similar colors, and may have an amber color body that creates a stunning blue-purple iridescence.

Especially rare forms of precious opals include harlequin opals (transparent to translucent opals with mosiac-like patches of color), crystal opals (completely transparent and gl...

Sometimes the matrix rock, or mother rock, like ironstone or sandstone creates bands or inclusions inside the opal. Some opal is cut to highlight such inclusions, but boulder opal is cut so the stronger matrix stone is only on the back of the cabochon, making the piece both more resilient and cheaper to purchase. Andean opal is another popular stone because of its turquoise color, usually opaque. It is believed that Andean opal will lose its color when exposed to air, so the stone is often “fixed” with a glue-like coating.

Fire opal is usually transparent and lacks the color play of other opals. It ranges in color from yellow to orange to red, with red being the most desirable. Fire opals, unlike precious opal, is often faceted and less expensive.

Common, or “potch,” opals come in three basic varieties: Honey opal, which has no color play and is often used in bead form; prase opal, which is a pretty green color thanks to the presence of nickel and has a cloudy look similar to that of chrysoprase; and seascape opal, which is a blue-green color, often with dendritic inclusions.

In medieval times, the opal was thought to bring great luck, possessing all the virtues of the various gemstones, thanks to the color play. It was believed that if you wrapped an opal stone in a fresh bay leaf, it could make you invisible. However, in Victorian times, the 1829 novel “Anne of Geierstein,” by Sir Walter Scott made the opal disreputable, described as a talisman that turned to colorless stone when touched by holy water—an event that killed the wearer. After his novel was published, the opal was believed to be a symbol of bad luck and death, and sales in Europe diminished.

Even in the early 20th century, fear and suspicion of the stone lingered, particularly with Russians, who thought the stone embodied the evil eye. That is perhaps why the opal appears in so few of the great jewelry collections of the 20th century.

The rebellious Art Nouveau artisans, though, rejected Victorian conventions and embraced the “organic” look of opal cabochons, which worked well with their insect motifs and elaborate enamel work.

Opals, being soft and subdued, are nearly the opposite of diamonds, with their hardness, brilliance, and fire. Yet these two stones complement each other well, particularly when a large opal cabochon is set within a protective ring of small, faceted diamonds.

Cartier made two pearl necklaces for Barbara Hutton featuring such opal-and-diamond clasps. One featured two rows of golden cultured pearls, and she would often wear this necklace with her beloved ruby and diamond tiara. The other was used on a strand of pearls once worn by Marie Antoinette and given to Hutton in 1933 by her father on the occasion of her marriage to Prince Alexis Mdivani.

Synthetic composite opals come in two forms: doublets and triplets. Doublets have an outer layer of precious opal, but a base of potch opal, whereas a triplet has a base of common opal, a thin layer of precious opal, and a protective covering of rock crystal. These composites can be identified by looking at them side-on with a magnifying glass.

In 1973, Gilson, the French company that developed imitation turquoise, also created imitation opal in the lab with nice iridescence but clearly fake color patterning. In the United States, John Slocum made a tough glass that resembled opal, but it lacked the texture of opal and looked crumpled under magnification. The cheapest fake opal around is made of polystryrene latex, which has a milky bluish sheen.

The most important factor in determining the quality of a piece of opal is the brightness and evenness of color. To check, turn the stone 360 degrees and make sure the iridescent color appears all across the surface, with no “dead” zones. For what it’s worth, “opalescence” is an incorrect term to apply to an opal; it refers to the the bluish-white shimmer, or “shiller,” on other gemstones, such as the moonstone.

Opals that have been drilled are more prone to dehydration, but it is possible to restore a dried-out opal by submerging it in water. Some evaporation is inevitable over time, but you can slow it by storing your opals in moist cotton balls. Opals are particular sensitive to perfume, soaps, and detergents, so opal necklaces and rings should be removed when washing or grooming.

About our sources | Got something to add?

▼ Expand to read the full article ▼

Best of the Web (“Hall of Fame”)

All About Jewels Dictionary

All About Jewels Dictionary

This incredible reference dictionary on jewelry, from Enchantedlearning.com, is both beautiful and comprehensive. S… [read review or visit site]

Morning Glory Antiques and Jewelry

Morning Glory Antiques and Jewelry

Jewelry collectors, feast your eyes on this internet gem! It's a goldmine of jewelry information featuring all styl… [read review or visit site]

Cathy Gordon's Jewelry Gallery

Cathy Gordon's Jewelry Gallery

With its vast galleries featuring clear images of jewelry and style, this site really covers it all! Divided up by … [read review or visit site]

Jewel History

Jewel History

Since March of 2007, readers of Lori Ettlinger Gross’s JewelHistory blog have been treated to her weekly (sometim… [read review or visit site]



Clubs & Associations

Other Great Reference Sites

Most watched eBay auctions    

Fine 22k Gold Black Opal RingRare Antique Estate Genuine Natural White Opal Bead Necklace 14k Gold ClaspVtg Victorian Revival 14k Gold 6 Carat Tw Australian Firey Opal Bangle BraceletSuperb Antique Large Fiery 14ct Gold Opal & Pearl Brooch No ReserveVintage 14k Gold Large Australian Green Fire Opal & 1/4 Carat Diamond NecklaceAntique 19thc. Victorian 18k Gold~opal & Old European Cut Diamond Ring~hallmarksFine Art Deco 18k Gold & Platinum Opal & Diamond RingGorgeous Early Gold & Opal Ring By Titantic Victim Ostby & Barton 10kFine 2.1/2 Carat Black Opal Doublet Gold RingVictorian Design Ladies Opal & Garnet 9ct Gold Cluster Ring F0822Gia 14.11 Ct Vvs Mexican Fire Opal Diamond 14k Gold Vintage Cocktail Estate RingLarge Stunning Opal Cabochon Ladies 9ct Gold Solitaire Ring F0807Fine Pair Of Art Deco 2.1/2 Carat Opal Gold EarringsStunning Art Deco Opal,ruby & White Sapphire Gold Pendant NecklaceFine Opal And Diamond 15ct Gold Pendant On ChainFine Art Deco Design Opal And Diamond Gold RingStunning French Art Deco 1.5 Carat Opal & 78 Point Diamond 18k Gold RingAntique Victorian 14k Gold White Opal And Rose Cut Diamond Cluster Pendant NrVintage 14k Gold Marquise Shape Firey Opal & Diamond Ladies Ring Size 6.5 Nr Mc2Fine Pair Of Opal Cabochon 9ct Gold Ladies Stud EarringsHeavy Vintage 14k Gold 1.50ct Diamond Opal Abstract Cluster Cocktail Ring Size 6Amazing Vintage 14k Gold Colorful Natural Australian Opal Fine Diamond PendantVivid Australian Opal Ring 14k Yellow Gold Estate Jelly Natural Cabochon CutFine Art Deco 6 Carat Opal Silver RingFine Art Deco Design Black Opal And Diamond 14ct White Gold Ring9ct Gold 6 Carat Opal Pendant And Chain.Fine Vintage Estate Jewelry: Pair 14k Yellow Gold & Opal Stud EarringsStunning Opal Caboboch 9ct Gold Ladies Stud Earrings F1272Vtg.solid 14k Gold 3ct. Opal Solitaire W/diamonds Ring Lot 4.2g.no Res! No Scrap10k Solid Gold Vintage Solid Natural Opal & Genuine Diamond Ring Sz 6.75 Vintage 5.50ct Lightning Ridge Australian Black Opal Diamond 18k White Gold RingFine Pair Of Art Deco Design Opal,amethyst & Turquoise Silver And Gold Earrings10k Solid Gold Top Quality Designer Natural Solid Opal Ring Sz 6.75 SpectacularBeautiful 9ct Gold Ladies Vintage Real Opal Ring Size KFine Opal And Emerald Gold RingVintage Pretty 9ct. Gold Single Opal Set Ring. Size - J. Very Good Condition.Vintage 14k Yellow Gold 21mm X 13mm Opal PendantVintage Old Pawn Navajo Flush Inlay Opal & Tigers Eye Sterling BraceletVintage Antique Art Deco 1930s Opal Red Opalescent Venetian Glass Bead NecklaceAntique 14k Gold,opal & Diamond Snake StickpinFine Opal & White Topaz Gold RingVintage Signed Zuni Sterling Silver Opal Sugilite Lapis Turquoise Pearl RingArt Deco 9 Ct / 9k Yellow Gold Opal Tear Drop / Dangling EarringsStunning Opal Cabochon Ladies 9ct Gold Cluster Ring F087018k Diamond Black Opal Sapphire Vintage Necklace Box Fine Vvs Huge 11.20 Carats Tested Antique 10kt Yellow Gold Jewelry Ring Opal Stone Size 6.5Fine Art Deco Design Opal, Emerald And Diamond Gold Cluster RingFine 3/4 Carat Opal Gold RingAntique Victorian Starburst Fiery Opal Seed Pearl 14k Yellow Gold Brooch Pin9ct Gold Real Heavy Vintage Opal And Garnet Ring Size MVintage 22k Gold Opal Pearl And Jade Pendant 7.3 Grams 1-7/8" By 3/4" 1.50 Ct Vivid Opal Solitaire Ring 14k Yellow Gold Estate Natural Cabochon CutFiery Opal Cabochon Ladies 9ct Gold Solitaire Cocktail Ring F0867Vintage Solid 14k Yellow Gold Fire Opal Push Back Earrings (1.1g) - 423581Ant.vtg.14k Eag .35ctw Garnet .96ctw Fiery Opal Cluster Ring,7.5 Grams,size 4Heavy Antique 14k Gold Elegant 7.49ctw Diamond/opal Brooch/pendantVintage Zuni Indian F Martinez Sterling Turquoise Gaspeite Sugilite Opal Ring 8 Vintage Delicate Opal & Gold Ring - Size PVintage Antique Art Deco 1930s Opal Opalescent Venetian Glass Bead NecklaceUnique 1940s Retro Deco Heavy 9k Gold Fiery Natural Australian Opal Ring