A huge light-blue gemstone which rests on top of a ring generally possessed by the rich and famous. (to the point that it was sold to it's current owner for five-million yen in India) However while the ring itself normally appears to be harmless, the exposure of the gem to the air builds up a negative chemical reaction until it causes a massive explosion every hundred years. While this typically would lead to the ring being destroyed to prevent this from happening, many factions wish to possess the ring to use this once-a-century event as a potential power source.