Certain gemstones have more vibration power at certain times of the year. The month of a stone's power time determines your birthstone (also referred to as natal stone).
Some believe that the original associations between gemstones and the months of the year evolved from 12 stones mentioned in the Bible, others say it represents the Twelve Apostles. Still others hold different beliefs. There are numerous traditions over the centuries that connect a particular gemstone with a month of the year.
For this reason, you will notice some stones listed under several months (all the stones associated with each month - whether traditional, talismanic, or other).
Month January
Garnet, Emerald, Rose Quartz, Onyx, Coral
Month February
Amethyst, Bloodstone, Onyx, Jasper, Imperial Topaz
Month March
Aquamarine, Bloodstone, Jade, Hematite, Ruby
Month April
Diamond, Opal, Crystal Quartz, White Sapphire, Moonstone
Month May
Emerald, Sapphire, Agate, Chrysoprase, Beryl, Carnelian, Garnet
Month June
Pearl, Moostone, Opal, Emerald, Turquoise
Month July
Ruby, Carnelian, Turquoise, Onyx
Month August
Peridot, Sardonyx, Diamond, Sapphire, Jade, Emerald, Aventurine
Month September
Sapphire, Agate, Moonstone, Lapis Lazuli, Diamond, Emerald, Peridot, Aquamarine
Month October
Opal, Tourmaline, Jasper, Pink Tourmaline, Zircon, Aquamarine, Agate, Garnet
Month November
Yellow Topaz, Citrine, Diamond, Tiger Eye, Amethyst, Amber, Aquamarine, Sapphire, Peridot
Month December
Blue Topaz, Turquoise, Zircon, Lapis Lazuli, Onyx, Ruby, Bloodstone, Chrysoprase