Turquoise (ter-kwoyz) is the birthstone for December.
Colors - light to medium blue, greenish blue to green: often mottled, and may show dark splotches or veins of matrix.
December - Turquoise
Blue Zircon
Blue Zircon (zur-con) is the alternate birthstone for December. I know, you've been told its blue topaz but its not. Blue Zircon is the true alternate December birthstone. Blue topaz is the gemstone typically used because it is much more common.
Colors - blue, yellow, green, brown, orange red and occasionally purple.