Sargon's Ruby, I think it was. It, if I remember correctly, caused him to flip from good to bad to good. I think. Maybe.
I just know there was a ruby. Wasn't there?
During some backstory about Nommo/Dr. Mist, of the Global Guardians, he was supposed to have been working behind the scenes for centuries, and imbuing gems with magical powers for others to use to do good. It would be neat if a few of the lesser-used 'magic gems' like the Ruby of Life used by Sargon, or the Blood Gem used by Bloodwynd turned out to be creations of Nommo, over the centuries!
I like how the 'Ruby of Life' under some writers seemed to impart a form of 'life' to inanimate matter, causing statues to walk, weapons to jerk free and attack their wielders, carpets to fly, curtains to wrap around foes, etc. Kind of a magic themed Life Lass, which is the kind of 'magic' character I like, one with a distinctive set of magical capabilities, and not just 'I do random stuff that works this week, and I'll forget I can do next week...'