Gemstones have lured mankind since ages not just for their aesthetic appeal but also for their exotic mysticism. In ancient ages gemstones were related to the occult and believed to influence the wearer with supernatural powers like attracting luck, warding off evil. The most general categorization of these gemstones was based on their color. Although different cultures had different beliefs here is a general distinction of gems based on color.

Yellow gemstones were believed to be symbolic of secrecy. The brighter hues of yellow were symbolic to the sun. Yellow also donated generosity. Yellow sapphires, yellow jacinth, chrysolite and citrine were the popular yellow stones.
True even today, white was believed to signify purity and peace. White was the gemstone associated to moon and pearl was the most celebrated of white stones.

Red colored gemstones were believed to be symbolic of command, royalty, lordship, and vengeance. The color was also associated to bravery and it was believed that a ruby would protect the wearer during a battle. With the hero gemstone being ruby other celebrated red stones were red garnet, lynx etc.
Blue was associated to wisdom and endurance. Blue sapphires were worn by kings to attract divine favor and help them make wise decisions.

Green typified verdure, youth and friendship.
Cleopatra, the most beautiful of her times cherished green stones typically emerald the most.
Purple was the color of sobriety and royalty. Wearing an amethyst was believed to free from addictive habits.
Black represented fortitude and mourning. Mourning jewelry of ancient times typically consisted of black stones.