Table:
text: Birthstones
Birthstones by cultures
Birthstones by cultures
Month_ _15th_20th_century U_S_1912 U_S_2013 Britain_2013 Hindu
January garnet garnet garnet garnet serpent stone
February amethyst , hyacinth , pearl amethyst amethyst amethyst chandrakanta
March heliotrope , jasper heliotrope , aquamarine aquamarine , heliotrope aquamarine , heliotrope Gold Siva-linga
April diamond , sapphire diamond diamond diamond , rock crystal diamond
May emerald , agate emerald emerald emerald , chrysoprase emerald
June cat`s eye , turquoise , agate pearl , moonstone pearl , moonstone , alexandrite pearl , moonstone pearl
July turquoise , onyx ruby ruby ruby , carnelian sapphire
August sardonyx , carnelian , moonstone , topaz sardonyx , peridot peridot peridot , sardonyx ruby

Question: What was the US birthstone in 1912 when the birthstone in 2013 was amethyst?

Question: In what month in 2013 did the US use the ruby birthstone?