Blue Topaz, Zircon, Turquoise & Tanzanite.
Blue is the overall color of December birthstones, though, zircon is available in a wide array of colors. Turquoise is the ancient December birthstone. Blue Topaz is among the more affordable options. Tanzanite is the newest gemstone, discovered in the 1960s in Tanzania, it is coveted for its deep, saturated blue to violet color.