I'm not joking, this design by Tobias Wong is really called 'Killer Engagement Ring'. It is a sturdy diamond ring whose point faces out, turning it into a potentially lethal weapon. The diamond sharp edge will cut skin down to the bone with a minimum of 1 karat stone - but the larger the stone the deeper the cut.
It can come in handy in serious situations like attempted rape or kidnapping. It can also be useful in scratching the hell out of your boyfriend's car if he ever cheats on you!