What is Opal?


Opal is a hydrated amorphous form of silica that is known for its stunning play-of-color. It’s primarily found in Australia, but it can also be sourced from other countries including Ethiopia and Mexico. Opal is often used as a gemstone and is a popular choice for jewelry due to its beautiful colors and spiritual significance.

Opal is a colorful gemstone known for its unique play-of-color. Its wide range of colors and intricate patterns make it a popular choice for jewelry and decorative items. The stone is often used in rings, necklaces, and pendants, and is sometimes used to make beads.

Gemstone Properties

Chemical ClassificationInorganic - Silicate (Hydrated silica)
ColorOpals can be colorless, white, gray, red, orange, yellow, green, blue, magenta, rose, pink, slate, olive, or brown. The play-of-color can display a wide range of hues.
StreakWhite to Light Blue
LusterSubvitreous to waxy.
TransparencyTranslucent to opaque.
OccurrenceAustralia, Ethiopia, and Mexico.
FormationTypically found in sedimentary rocks, but can also be found in volcanic rocks.
DiaphaneityTranslucent to opaque with play-of-color
Mohs Hardness5.5-6.5.
Specific GravityApproximately 1.98 to 2.25.
Diagnostic PropertiesPlay-of-color.
Chemical CompositionSiO2·nH2O
Crystal SystemAmorphous
Optical PropertiesIsotropic (due to its amorphous nature)
Refractive Index1.440 - 1.460
BirefringenceNone (isotropic due to amorphous nature)
2V angleNot applicable (amorphous)
DispersionNot typically relevant for opals due to their play-of-color.