Adjacent amethyst and citrine colors in the same crystal of quartz have been reported from South America, although there appears to be uncertainty as to the exact locality of origin. Such material has ...
Amethyst may develop into the more common citrine and rarer green quartz naturally under certain geologic conditions. On the California-Nevada border, just north of Reno, amethyst, citrine, and green ...
Unless you have a lab at your disposal to determine the refractive index and specific gravity of a given stone ... colors both natural and artificial. Thus, when looking for jewelry with a ...