Opal

Q: What is Opal?

El ópalo es una forma amorfa de sílice hidratada cuyo contenido de agua oscila entre el 3 y el 21%, y es célebre por su juego de colores —la opalescencia— producido por la difracción de la luz en microesferas ordenadas de sílice. Clasificado como gema preciosa en Roma, la India y Arabia, fue la pied

Q: What is the hardness of Opal?

Opal has a Mohs hardness of 5.0 to 6.5, making it moderate for use in jewelry.

Q: Where is Opal found?

Opal is found in Lightning Ridge (Australia).

Q: How much does Opal cost?

Opal falls into the Budget (< $50/ct) price range. Prices vary based on color, clarity, cut, and origin.

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A hydrated amorphous silica, opal is celebrated for play-of-color, a shifting spectral display of red, green, blue, and gold produced as light diffracts through ordered arrays of microscopic silica spheres. Australia yields roughly ninety percent of the world's precious opal, including white opal from Coober Pedy, black opal from Lightning Ridge, and boulder opal from Queensland, with further sources in Ethiopia and Mexico. Lacking crystalline structure, it measures 5.0 to 6.5 on the Mohs scale. Revered since antiquity and the birthstone for October, opal is classed as semi-precious in the budget tier, yet fine black opal with red fire ranks among the most valuable colored stones per carat.

Physical & Optical Properties

Category Semi-Precious Gems

Mohs Hardness 5,0 – 6,5

Specific Gravity 1,98 – 2,25

Refractive Index 1,37 – 1,52

Crystal System Amorphous

Cleavage None

Fracture Conchoidal,Splintery

Color white

Pleochroism Absent

Mohs Hardness

Mohs Hardness: 5,0 – 6,5

1 Soft10 Hard

Crystal System

Value & Market

Price Tier Budget (< $50/ct)

Where to Buy Opal

Blue Nile Fine jewelry retailer

James Allen Gemstone jewelry

Brilliant Earth Ethically sourced gems

Amazon Wide selection

Links may earn a commission at no extra cost to you.

Cultural Significance

Birthstone Month 10 (modern)

About Opal

El ópalo es una forma amorfa de sílice hidratada cuyo contenido de agua oscila entre el 3 y el 21%, y es célebre por su juego de colores —la opalescencia— producido por la difracción de la luz en microesferas ordenadas de sílice. Clasificado como gema preciosa en Roma, la India y Arabia, fue la piedra preciosa más valorada durante siglos hasta que la apertura de las minas australianas revolucionó su disponibilidad en el siglo XIX. Australia produce más del 90% del ópalo precioso mundial, con los tipos más apreciados siendo el ópalo negro de Lightning Ridge y el ópalo de matriz de Andamooka.