The Gem of Light, Color, and Mystery

Opal is unlike any other gemstone on Earth. With its play-of-color, glowing iridescence, and almost supernatural depth, Opal has captivated humanity for millennia. Ancient legends claimed it fell from the heavens. Poets called it a “lightning in stone.” And in the world of fine gems, Opal remains the only stone that contains every color of the rainbow—shimmering in motion with every turn of the wrist.

No two opals are alike, and that’s part of their magic. Each one is a tiny world of color, fire, and mystery—making it one of the most personal and emotionally evocative gems you can own.

🔬 Scientific Profile

Opal is a hydrated amorphous form of silica with the chemical formula SiO₂·nH₂O. It contains up to 20% water and forms from a solution of silicon dioxide and water that seeps into cracks in rocks. Over time, it hardens into a gel-like structure, often inside cavities, fossils, or volcanic rocks.

It ranks between 5.5 and 6.5 on the Mohs hardness scale, making it softer and more delicate than most gemstones. Its refractive index ranges from 1.37 to 1.52, and its specific gravity typically falls between 1.98 and 2.25. Because of its unique structure, Opal does not form crystals, and its famed play-of-color is caused by the diffraction of light across microscopic silica spheres arranged in a regular pattern.

Unlike any other gemstone, Opal displays dynamic flashes of color that seem to come alive as it moves. This optical effect is called opalescence or play-of-color, and it's what sets fine opals apart.

🌈 Color and Variety

Opal comes in a stunning range of varieties—each defined by background color, body tone, transparency, and the intensity and pattern of its play-of-color.

Black Opal is the most valuable and rare variety. Found almost exclusively in Lightning Ridge, Australia, it features a dark body tone—black, gray, or dark blue—that amplifies the play-of-color across its surface. Vivid flashes of red, green, and violet dance against the dark background, giving it depth and dimension that is unmatched.

White Opal, also called Light Opal, has a milky or pale background and is the most traditional and widespread variety. Its play-of-color tends to be more pastel and subtle, though high-quality stones can still display bright rainbow flashes.

Crystal Opal is transparent to semi-transparent with vivid play-of-color visible throughout the body of the stone. It often appears as though the colors are floating within glass, offering ethereal beauty and glowing saturation.

Fire Opal is a unique variety found mostly in Mexico, with a warm body color ranging from orange to red. While some fire opals show play-of-color, many are prized simply for their bold, juicy tones and transparency.

Boulder Opal is found in ironstone matrix rock in Queensland, Australia. The opal forms in thin seams or veins through the host rock, and the matrix is left attached during cutting. The result is a striking contrast of earthy browns and electric color flashes.

Ethiopian Opal, especially from the Welo region, has gained popularity for its translucency, hydrophane nature (it can absorb water), and remarkable color patterns. These opals are often honey-colored when dry but can temporarily change when exposed to moisture.

Common Opal, also known as “potch,” has no play-of-color and is valued for its soft pastel hues—like pink, blue, green, or lavender. Though more subtle, it is still prized for cabochons and artisan jewelry.

📜 History and Symbolism

Opal has a long and dramatic history. The Romans treasured it as the most powerful of all gemstones, believing it held the virtues of every stone whose color it contained. The name “opal” is derived from the Latin opalus and the Sanskrit upala, meaning “precious stone.”

In ancient Arabia, people believed Opals fell from the sky during lightning storms, capturing the power of the heavens inside them. In ancient Greece, they were thought to grant the power of foresight and protection. In Europe, Opal symbolized purity and hope and was considered a lucky charm for centuries—until superstitions in the 19th century gave it a reputation for bad luck, a myth long since debunked.

Today, Opal represents passion, creativity, and spontaneity. It is said to enhance imagination, release inhibitions, and amplify emotional expression. Opal is the birthstone for October and the traditional gemstone for the 14th wedding anniversary.

💎 Opal in Jewelry

Due to its softness and sensitivity to moisture, Opal requires thoughtful handling and secure setting. It’s best worn in pendants, earrings, and rings with protective designs. Despite its fragility, Opal remains one of the most mesmerizing and artistic stones in the world of jewelry.

Cabochon is the most popular cut for Opal, allowing the full range of play-of-color to be displayed across a smooth, domed surface. However, freeform cuts and designer shapes are also common, particularly in boulder and fire opals.

Opal pairs well with diamonds, sapphires, and other colored gems, and looks stunning in both white and yellow metal settings. No two opals are alike—making every Opal jewelry piece as individual as the person who wears it.

Collectors especially prize high-grade black opals, large crystal opals, and unusual pattern stones (like harlequin or flame patterns) for their rarity and investment potential.

✨ Experience the Magic of Opal at Chicago Gems & Jewelry

At Chicago Gems & Jewelry, we offer a curated selection of exquisite Opals—from the glowing depths of Australian black opal to the radiant hues of Mexican fire opal and the luminous charm of Ethiopian Welo opal. Each stone is hand-selected by our GIA graduate gemologist for its brilliance, pattern, stability, and natural beauty.

Whether you're searching for a one-of-a-kind ring, a statement pendant, or a timeless October birthstone gift, we are here to guide you to the perfect piece.

Family owned and operated since 2008, our Crystal Lake showroom has earned a reputation for integrity, expertise, and personalized service.

Chicago Gems & Jewelry – Where Knowledge Meets Beauty, and Every Stone Tells a Story.