Zircon is another gem that serves as a birthstone for the month of December. It is a bright gem with high luster, and many specimens produce a colorful fire that is similar to diamond. Because of these properties, zircon was once used as an alternative stone for diamond.

Zircon gives the shopper an opportunity to select from a variety of colors. Blue is the most popular zircon color. Most natural zircons are yellow, red or brown, but heat and irradiation treatments can transform them into blue, green and many other colors. About 80% of the zircons sold today are blue, with the color produced by treatment. Zircon replaced lapis lazuli as a modern birthstone in 1952.