Research shows that the birthstone list has its origins in the Zodiac and astrology, composed by Josephus. Saint Jerome is reported to have offered a Christian version of the list based on the stones of New Jerusalem and the 12 Apostles. Unfortunately we do not have a copy of that list today, and it is possible that that list was related to the signs of the Zodiac as well. I’ve composed this new zodiac-free list based on St. Jerome’s ideas about the New Jerusalem stones and the 12 Apostles, using their feast days and matching each of them to one of the New Jerusalem stones and a virtue we can learn from their life. Since some of the Apostles share a month, I filled in the blanks with Apostle-like saints who were crucial in the formation of the Church and additional gemstones to represent them. You can wear your new birthstone to honor your birth Apostle and pray to master his virtues.
January — Timothy and Titus — topaz — responsibility
February — Matthias — jasper — hope
March — Epaphroditus — sapphire — charity
April — Mark — carnelian — repentance
May — Philip and James the less — chalcedony/agate — wisdom
June — Peter and Paul — emerald — evangelization
July — Thomas and James the greater — sardonyx — courage
August — Bartholomew — beryl/aquamarine — honesty
September — Matthew — chrysolite/peridot — devotion to Scripture
October — Simon and Jude — chrysoprase — faith
November Andrew — hyacinth: (jacinth/zircon)(ligure/amber) — endurance
December — John — amethyst — love