Your Purchases
White Opal is a hydrated amorphous form of silica (SiO2·nH2O) characterized by its milky-white to translucent appearance and distinctive play of colors known as opalescence. This precious gemstone exhibits a unique internal structure of uniformly sized silica spheres arranged in a regular pattern, creating diffraction of light that produces its characteristic spectral display.
The stone forms in the fissures of rocks when silica-rich water penetrates the ground and deposits microscopic spheres of silica gel. These spheres, ranging from 150 to 300 nanometers in diameter, stack in a cubic or hexagonal close-packed structure. The white base color results from the presence of tiny air bubbles trapped between the silica spheres, which scatter light diffusely. The stone’s hardness ranges from 5.5 to 6.5 on the Mohs scale, with a specific gravity between 2.1 and 2.2, distinguishing it from other varieties of precious opal.
White opal is a natural form of opal, but can be synthesised.
Common names for White Opal include Milk Opal, White Milk Opal, and Pearl Opal.
White Opal has a hardness of 5.5 to 6.5 on the Mohs scale, which makes it relatively softer than many other gemstones. This level of hardness suggests that while opal is reasonably durable, it requires care in handling to avoid scratches.
The refractive index of White Opal ranges from 1.37 to 1.52. This range contributes to the gemstone’s unique play of color, a characteristic optical phenomenon of opals.
White Opal exhibits a luster that can range from waxy to pearly. The luster contributes to its beautiful visual appearance, enhancing its play of color.
Opal, including White Opal, generally does not have any cleavage. This means that it does not have natural planes along which the stone splits easily.
White Opal typically has a conchoidal to uneven fracture. This type of fracture can produce a smooth curved surface when the opal is broken.
The specific gravity of White Opal can vary between 1.98 and 2.20. This parameter helps in distinguishing real opal from imitations.
Opal, including White Opal, is amorphous and does not exhibit birefringence. They do not have a crystalline structure necessary to cause double refraction.
White Opal can display a remarkable dispersion or fire, which is the play of spectral colors. The fire is one of the most sought-after qualities in opals.
Opal is amorphous, meaning it does not have a crystal system. It is composed of silica spheres that are orderly stacked, which contributes to the play of color.
White Opal typically shows a light body color which can range from colorless to white, and occasionally it includes other pale hues.
White Opal can range from opaque to translucent. The level of transparency affects the play of color and the overall visual appeal of the gemstone.
Opal, including White Opal, does not exhibit pleochroism due to its amorphous nature.
White Opal can show weak to moderate fluorescence under UV light, typically displaying a white or greenish hue.
White Opal has fair to good toughness, but care should be taken in handling and setting as the gem can be sensitive to pressure and impact.
White Opal is generally brittle, which aligns with its conchoidal fracture and amorphous structure.
Being amorphous, White Opal is isotropic and does not show an optic sign.
White Opal does not typically display a characteristic absorption spectrum due to its amorphous nature.
White Opal is a hydrated form of silica (SiO2·nH2O). Its water content can range from 3% to 21% by weight.
Although less common in White Opal compared to other varieties like Tiger’s Eye, some opals may exhibit a cat‚Äôs eye effect when cut appropriately.
Asterism or the star effect is generally not observed in White Opal.
White Opal is well-known for its iridescence. This optical phenomenon is due to the diffraction of light passing through the microscopic layers of silica spheres within the opal.
White Opal is not magnetic.
As a type of silica, White Opal is an electrical insulator.
White Opal is not radioactive.
