Birthstones are gems that people traditionally associate with a certain month. Birthstones may be precious or semi-precious, regarding the value of the stone. Modern birthstone lists may differ slightly from older or more traditional birthstones. While some birthstones are typically shades of a specific color, others may be many hues, depending on the type of gem.
January Through April
The birthstone of January is garnet, one gem that can come in a range of colors. Garnets can be shades from a deep red to a brilliant green.
February's birthstone, the amethyst, is a purple-colored type of quartz---the color purple is traditionally linked to royalty.
March has two birthstones: aquamarine, a gem the color of water, which may be light blue to a bluish-green hue, and bloodstone, which gets its name from its bright red specks in dark green stone.
Diamonds, the birthstone of those born in April, form in a number of colors, though some diamonds have coloring introduced through artificial means.
May Through August
At one time, the emerald, a green birthstone of May, was reportedly so soothing to gaze upon that gem cutters would look at the stones to rest their tired eyes. Emeralds of high quality are very expensive and are in limited supply; it is thus often necessary to attempt to improve the clearness of existing inferior stones.
Alexandrite, June's birthstone, is a unique birthstone. It will appear green in daylight, but under incandescent light changes to a purple-red color. June's other birthstones, the pearl and the moonstone, both come in an array of colors and have a shimmering quality to them.
The ruby is second in hardness among gemstones only to the diamond and is thus used in mechanical application such as watches; this July birthstone varies from dark shades of red to a reddish-purple shade.
The peridot, August's birthstone, forms in many shades, ranging from green-yellow to brown. Lime green is the most popular color for this stone, according to the American Gem Society.
September Through December
September's birthstone is the sapphire, which is composed of the same mineral from which rubies come---corundum---but are different colors. Sapphires can be pink, green, orange or several other colors, but blue stones are the most valuable.
Perhaps no birthstone comes in as great a range of colors as October's: The opal may be a creamy white to almost black. Opals have a shimmering, multicolored appearance, and most are mined in Australia.
The topaz, a November birthstone, is another gem with multiple shades, including blue, yellow, green, purple and pink. Citrine, an alternative birthstone for November, is an abundant gem that comes in shades of yellow.
December's birthstones---turquoise and Tanzanite---both have shades of blue. Light blue, often speckled or veined with green or gray, is the predominant shade of turquoise stones. Tanzanite, a more recently discovered gem, is a blue-violet hue.