The December birthstone is composed of six different gemstones: TURQUOISE (9 letters), ZIRCON (6 letters), TOPAZ (5 letters), OPAL (4 letters), GARNET (6 letters), and RUBY (4 letters). TURQUOISE is a blue-green mineral that has been used in jewelry for centuries. ZIRCON is a colorless gemstone that is often mistaken for diamonds. TOPAZ is a yellow-orange gemstone that is known for its brilliance and clarity. OPAL is a gemstone that displays a rainbow of colors when light is shone through it. GARNET is a deep red gemstone that is believed to bring good luck. Finally, RUBY is a deep red gemstone that is known for its hardness and beauty.