Ancient civilization were fascinated by the exceptional hardness of diamond, although colored gems were regarded as more aesthetically pleasing. Diamond was extremely rare up to the eighteenth century and was only fully appreciated after the modern type of brilliant cut, w... 

Corundum often contains very fine needles of rutile arranged in intersecting lines in accordance with the symmetry of the crystal. These apparently developed when the storm is formed: as the temperature falls, the TiO2 is no longer soluble in the Al2O3 and forms separate cry... 

True topaz or yellow topaz is the most typical variety, and no adjectives are needed to describe its color, although different shades are referred to as “golden topaz” or “sherry topaz”. Appearance:The color can range from golden to honey yellow or ... 

It has one of the color ranges in the mineral world. The most common color is black, but tourmaline may be pink, violet-red, brownish yellow, blackish brown, various shades of green, light blue, blue-green, dark blue, and (rarely colorless). Fine crystals with concentric z...