January
 Garnet
February
 Amethyst
March
 Aquamarine or Bloodstone
April
 Diamond
 
  
May
 Emerald
June
 Pearl, Moonstone or Alexandrite
July
 Ruby
August
 Peridot
 
  
September
 Sapphire
October
 Opal or Tourmaline
November
 Citrine or Topaz
December
 Turquoise, Zircon or Tanzanite

For detail description of the birthstones, including their myth, magic and legends click on the following link, http://www.jic.org/index.php?page=birthstones.