Some history and a bit of magic from the annals of Arduin.
A purplish Trapezohedron looted from an abandoned ship found floating in the Orchalcum Ocean without a crew. While the ship showed signs of battle and was gutted by flame in the hold, it was still seaworthy. The Chorynthian merchanteer that came across it sank the ship afterward, following an aborted attempt to tow it back to a port and an encounter with pirates. Supposedly the gem took the name Sargo'oth from the bastardization of words written on parchment that was that was wrapped around the gem was found. The Chorynthian captain dubbed it Sargo'oth's Nail when he used it as an impromptu dagger during the later struggle with pirates. Reputedly, it could pierce any material from fine Bossalian Steel to paper with ease and suck the magic out of anything it touched.