Black onyx is chalcedony that has been dyed or sugar-acid treated.
Black Onyx Classification
||Black Onyx |
Black Onyx Optical Properties
Black Onyx Characteristic Physical properties
Sardonyx is a form of onyx that is made up of bands of red sard and white chalcedony. Because ofits banded patterns, sardonyx has been used for years in making cameos.
Sardonyx Characteristic Physical properties
||Sardonyx has white and/or black bands alternating on carnelian or sard colors and this is what separates sardonyx from other calcedonies. |
Chrome chalcedony contains chromium, normally seen in the most coveted gems in the world; namely alexandrite, emerald and ruby. Present in small amounts, chromium gives these stones their unique shades of green, which have been compared to green seawater. Chrome chalcedony is usually untreated, as absolutely nothing is required to make this stone desirable! Although chrome chalcedony somewhat resembles chrysoprase in appearance, the two receive their color from two different elements.
Chrome Chalcedony Classification
||Chrome Chalcedony |
Chrome Chalcedony Optical Properties
||Light grayish pink or reddish |
Chrome Chalcedony Characteristic Physical properties
||Chrome chalcedony might contain black chromite crystals. Look for lack of dye concentrations to separate from dyed chalcedony. |
Also referred to as "damsonite," amethystine chalcedony is an opaque to semi-translucent variety that is, you guessed it, purple. As chalcedony is technically a quartz, this gem is much like traditional amethyst and even can be heat treated to become a yellowish orange citrine color.
Amethystine Chalcedony Classification
||Amethystine Chalcedony |
Plasma is the term for a deep green chalcedony that often shows small yellow, red or white spots.
Plasma Optical Properties
Plasma Characteristic Physical properties
||Plasma is dark green with white or yellowish spots.The stones semi transparent to opaque nature is what separates plasma from other chalcedony varieties. |