January

This stone gets its name from the Latin word for pomegranate, since its crystals often resemble the fruit's deep-red color and seeds.  But garnets come in many colors and can even be colorless.  Garnets are thought to protect sleepers from nightmares and travelers from danger.

February

This gem is made of quartz, the second most abundant mineral on Earth.  Its color ranges from wine-purple to pale lilac; the deep shades are most valuable.  According to mythology, Diana, goddess of the hunt, turned a maiden named Amethyst to quartz, saving her from Dionysus, the god of wine.  His tears stained her purple.  The stone is thought to represent sobriety.

March

Aquamarine gets its blue color from iron; its crystals can grow as large as 200 pounds.  It is thought to protect ocean voyages, guard against sea monsters and soothe marital discord.

April

The hardest natural substance on Earth, a diamond's colors range from clear to sooty black.  Ancient cultures believed the gems were crystal lightning, splinters of stars, and tears of the gods.

May

This green stone is often fragile, due to fissures and fractures.  Transparent gems are extremely rare.  The emerald is a symbol of rebirth and romance.  It is thought to soothe the soul, sharpen the wit - and change color upon infidelity.

June

The pearl is formed inside the shell of a mollusk, from an irritant coated with calcium carbonate.  Pearls vary widely in color and shape.  The pearl is the Chinese symbol of wealth, power and longevity.

July

Second only to diamonds in hardness, rubies can be even more valuable, especially when they are large and of high quality.  The red stone is a symbol of wealth, health, wisdom, passion and the triumph of love.  It is also said to ring good luck to gamblers.

August

Peridot is a green stone with an oily luster.  It is sometimes called the "evening emerald".   It is considered an amulet against night terrors.

September

A gem belonging to the corundum family, sapphire can be any color but red (because red corundum is ruby).  Blue gems are the finest.  Considered a symbol and guardian of purity, the stone has been worn by clergy to avoid temptation.

October

Opal is a fragile stone of silica and water.  Opals symbolize magic, love and hope.  Some believe that wearing them is unlucky for those not born in October.

November

Trace minerals create topaz gems in colors from blue and green to pink, sherry and even black.  Topaz is the sun jewel.  It reminded the Egyptians of Jupiter.  It is thought to improve eyesight and break spells.

December

Turquoise, a gem mined in arid and semiarid lands, ranges in color from blue to green.  In the third century, turquoise was thought to protect its owner from falling off a horse.

Alternative for March

Sometimes called heliotrope, or blood jasper, it is opaque quartz with flecks of red from iron.  It signifies martyrdom.

Alternative for June

Moonstones can be semi-transparent to opaque.  Hindus believed that moonstones were bits of moonbeams.

Alternative for June

Alexandrite gems are very rare and are known for chameleon-like color changes.

Alternative for August

Onyx is an opaque quartz.  Carved with images of Mars, god of war, onyx supposedly gave Roman soldiers courage.

Alternative for October

Tourmaline has many colors and can even be multicolored within a single stone. It is said to protect against bad decisions.

Alternative for November

Citrine is an affordable, yellow-orange gem.  It is believed to guard against snake venom and evil thoughts.

Alternative for December

Zircon is fiery and has a wide range of colors.