Traditional birthstones are listed first, followed by some of the modern alternatives. 

January: Garnet, Emerald, Hyacinth

February: Amethyst, Bloodstone

March: Aquamarine, Bloodstone, Jasper, Jade

April: Diamond, Opal, Sapphire

May: Emerald, Sapphire, Agate, Carnelian, Chalcedony

June: Pearl, moonstone, Alexandrite, Agate, Chalcedony, Emerald

July: Ruby, Carnelian, Onyx, Sapphire, Sardonyx

August: Peridot, Sardonyx, Diamond, Sapphire, Carnelian, Ruby, Alexandrite

September: Sapphire, Agate, Moonstone, Chrysolite, Zircon, Sardonyx

October: Opal, Tourmaline, Jasper, Aquamarine, Coral, Beryl

November: Yellow Topaz, Citrine, Pearl, Topaz, Cat's-eye

December: Blue Topaz, Turquoise, Tanzanite, Zircon, Lapis, Onyx, Ruby, Topaz, Chrysoprase