A ruby is a pink to dark red hued gemstone, derived from the mineral corundum (aluminum oxide). Different kinds of the same mineral corundum are called sapphires. Ruby is one of the "cardinal" jewels, along with amethyst, sapphire, emerald, and diamonds. The word ruby comes from ruber, Latin for red. The shade of a ruby is red because of an additional component of chromium.
Rubies have a hardness of 9.0 on the Mohs scale of mineral hardness. Among the natural gems only moissanite and diamond are harder, with diamond having a Mohs hardness of 10.0 and moissanite falling somewhere in between corundum (ruby) and diamond in hardness.
All natural rubies have imperfections in them, including color impurities and inclusions of rutile needles known as "silk". Gemologists use these needle inclusions found in natural rubies to distinguish them from synthetics, simulants, or substitutes. Usually, the rough stone is heated before cutting. These days, almost all rubies are treated in some form, with heat treatment being the most common practice. Untreated rubies of high quality command a large premium.
Some of the earliest recorded transport and trading of rubies can be found in literature. About 200 BC rubies were recorded being carried along the Chinese Silk Road which was an ancient travel path moving westward out of China.
Rubies have always been held in high esteem in most Asian countries. They were used to ornament armor, scabbards, and harnesses of noblemen in India and China. Rubies were placed beneath the foundation of buildings to bring good fortunes to the structure.
A traditional Hindu belief says rubies are the "gemstone of the Sun". The belief is that wearing rubies causes the Sun to be favorable to the wearer. The perfect jewel for our sunny Florida home!