Asterism
An effect of some polished cabochons that cause a reflection like a star which moves when rotated.
Asterism is caused by dense inclusions of tiny fibers in the mineral.
Minerals with asterism: Ruby, Moonstone
Ruby in the left and Moonstone on the right
Adularescence
Optical effect exhibited on certain minerals and gemstones where they display a ghost-like reflection with a bluish-white color emanating from surface, effect caused by anomalies in its structure or build up of water.
Minerals with adularescence: Opal and Moonstone
Chatoyancy / chatoyance or cat's eye effect / cat eye effect
Effect of cat's eye in minerals causing a white reflected band across the center of the mineral, almost exclusively in polished cabochons.
Minerals: Moonstone, Chrysoberyl, Tiger's eye
Iridescence / goniochromism / iridiscenta / opalescence / opalescenta
A phenomena of a mineral to show a rainbow of colors when is turned around.
Minerals: Bismuth (oxide crystals - element), goethite (when oxidizes), opal
On opal, the phenomena is named opalescence
Tenebrescence / tenebrescenta / photochromism / fotocromatism
Also named photochromism, is the ability of some minerals to change color after is exposed to natural light or when under ultraviolet light, will temporally have a darker or change of color.
The phenomena can be repated indefinelly but it is destroyed by heating.
Minerals: Hackmanite (variety of sodalite), Spodumene, Tugtupite, Sodalite
This effect is used synthetically in sunglasses.
Pleochroism / dichroism
A mineral exhibiting two or more colors when viewed at different angles
Dichroism refers to only two colors.
Mineral: Junzite (spodumene variety)
Double refraction
Apears two refraction lights in clear samples
The two refractions are different polarization ungle.
Minerals: calcite, aragonite
An effect of some polished cabochons that cause a reflection like a star which moves when rotated.
Asterism is caused by dense inclusions of tiny fibers in the mineral.
Minerals with asterism: Ruby, Moonstone
Ruby in the left and Moonstone on the right
Optical effect exhibited on certain minerals and gemstones where they display a ghost-like reflection with a bluish-white color emanating from surface, effect caused by anomalies in its structure or build up of water.
Minerals with adularescence: Opal and Moonstone
Moonstone
Chatoyancy / chatoyance or cat's eye effect / cat eye effect
Effect of cat's eye in minerals causing a white reflected band across the center of the mineral, almost exclusively in polished cabochons.
Minerals: Moonstone, Chrysoberyl, Tiger's eye
Chrysoberyl
A phenomena of a mineral to show a rainbow of colors when is turned around.
Minerals: Bismuth (oxide crystals - element), goethite (when oxidizes), opal
On opal, the phenomena is named opalescence
Tenebrescence / tenebrescenta / photochromism / fotocromatism
Also named photochromism, is the ability of some minerals to change color after is exposed to natural light or when under ultraviolet light, will temporally have a darker or change of color.
The phenomena can be repated indefinelly but it is destroyed by heating.
Minerals: Hackmanite (variety of sodalite), Spodumene, Tugtupite, Sodalite
This effect is used synthetically in sunglasses.
Pleochroism / dichroism
A mineral exhibiting two or more colors when viewed at different angles
Dichroism refers to only two colors.
Mineral: Junzite (spodumene variety)
Double refraction
Apears two refraction lights in clear samples
The two refractions are different polarization ungle.
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