Answer:
Month 15th- 20th century[4]:315 U.S. (1912)[4]:319–320 U.S. (2019)[10] Britain (2013)[11]
January garnet garnet garnet garnet
February amethyst, hyacinth, pearl amethyst amethyst amethyst
March bloodstone, jasper bloodstone, aquamarine aquamarine, bloodstone aquamarine, bloodstone
April diamond, sapphire diamond diamond diamond, rock crystal
May emerald, agate emerald emerald emerald, chrysoprase
June cat's eye, turquoise, agate pearl, moonstone pearl, moonstone, alexandrite pearl, moonstone
July turquoise, onyx ruby ruby ruby, carnelian
August sardonyx, carnelian, moonstone, topaz sardonyx, peridot peridot, spinel peridot, sardonyx
September chrysolite sapphire sapphire sapphire, lapis lazuli
October opal, aquamarine opal, tourmaline opal, tourmaline opal
November topaz, pearl topaz topaz, citrine topaz, citrine
December bloodstone, ruby turquoise, lapis lazuli turquoise, zircon, tanzanite tanzanite, turquoise
Explanation: