RUBY BELONGS TO THE CORUNDUM MINERAL FAMILY, AS DOES SAPPHIRE. THESE TWO GEMS ARE THE HARDEST AFTER DIAMOND.

SAPPHIRE IS A VARIETY OF GEMSTONES THAT CAN EXHIBIT MULTIPLE COLORS, EXCEPT FOR RED, WHICH IS THEN EXCLUSIVELY REFERRED TO AS RUBY.

EMERALD IS A MINERAL OF THE BERYL FAMILY, LIKE AQUAMARINE. EMERALD IS THE MOST PRECIOUS OF THE BERYLS.