Opal Doublet Gemstone & Information | Gemopedia by JTV | Gemopedia™
An opal doublet is an assembled gem that consists of a thin slice of natural opal attached to a second layer of material with a bonding agent. The types of materials used for opal doublets vary considerably but may include ironstone, sandstone, black plastic or quartz. Opal doublets often provide a more affordable alternative to solid opals and are often used today for mass-produced jewelry.
Variety Of Colors
Opal-doublet classificationCommonNameOpal DoubletSpeciesOpal DoubletVarietyColorsVariety Of ColorsAlternateNamesGemstoneGroupsKeySeparationsAppearance and magnificationClassificationCommentsThe base of opal doublets can be made of potch opal, dyed black chalcedony, glass or other matrix materials.
Opal-doublet chemistry & crystallographyChemicalNameChemicalFormulaSiO2-nH2O with baseSynthesisassembledCrystalSystemNAChemistryClassificationNatureCompositeCrystallinityChemistryComments
Opal-doublet optical propertiesTransparencySemitranslucent - OpaqueDispersionOpticalCommentsRefractiveIndex1.45
Tolerance:-0.25BirefringenceOpticCharacterNAOpticSignPolariscopeReactionSingly Refractive (SR)FluorescenceSWUV:
Opal-doublet characteristic physical propertiesHardnessCharacteristicCommentsStreakSpecificGravityToughnessInclusionsLook for assembled nature and glue layer in opal doublets. Look for straight separation planes to distinguish opal doublets from natural opal that contain a potch opal under layer. These stones might have areas of potch or matrix that lack play-of-color. Synthetic opal will have a more uniform play-of-color appearance. Stones are sometimes glued using black cement to give the appearance of a black opal.LusterVitreousStabilityFractureCleavageNone