Your Starstone is the EMERALD.

Emeralds from Egypt are known to date from about 330 B.C., and indirect evidence suggests that Egyptians were mining emerald as early as 1300 B.C. The name emerald comes from the greek smaragdos meaning "green stone" and probably referred, in fact,not just to emeralds but to all or many green gems. Emerald boasts a great deal of folklore. It was used as a burnt offering, a symbol of St. John, and supposedly was a poison antidote, a cure for fevers and epilepsy, eye relief (due to the exceptional color), a cure for dysentery and leprosy, a cure for ophthalmia and bleeding, a cure for stomach problems (when laid on the stomach), and a good laxative.