The fic(s) in question are my "Heroes of Arcadia" series. I used the Emeralds for inspiration for the design for something called the Descendancy Medallion. You can read how the series starts by reading the fic "Heroes of Arcadia - The Gamemaster's Legacy". My fics are all on Fanfiction.net. Note: I am in the process of rebooting the series, so the fic is badly outdated.