Heat up a needle on the stove,
more or less-insert into the fingernail and relive the pressure and be done with it. it'll hurt a bit, but you wont die. onec that blood makes it way outta your finger, You'll feel the pressure come off and like a new man! hahahaha
I've squeezed my fender quite a bit, and I can't seem to get any blood out of it. Not too sure about taking a drill bit or hot needle to it, though...
I've had a couple of those purple finger incidents in the past - once got smooshed in a closing car door, another time involved a wrench that slipped while fighting a brake caliper bolt and smashed against a tie rod end. Both times I just babied the damaged fingers for a couple of weeks, and it all just kind of went away on its own. Never lost a fingernail, and never had to bother with the hot needle/drill bit trick. Maybe it just depends on the severity of the injury, or something...?