First Class Precious Stones: Quartz- Colored Varieties

When crystals of quartz are found combined with certain traces of colouring matter, they constitute distinct species in commerce, and take completely different names.

Combined with iron and alumina quartz becomes yellow, and takes the name of the occidental or Bohemian topaz.

Impregnated with a bituminous substance it becomes more or less darkened, and is called the smoky topaz, or Alencon diamond.

Combined with a slight proportion of oxide of manganese it takes a beautiful violet colour; it is then the occidental amethyst.

Coloured blue by iron and alumina, it becomes the water sapphire.

Coloured rose by iron and manganese, it is the Bohemian or Brazilian ruby.

Combined with a notable proportion of oxide of iron, it becomes a brown red, and constitutes the hyacinth of Compostella.

But among all these varieties there are only two that are really valuable--the amethyst and the water sapphire.