I own a jade comb. I've examined it thoroughly, and its hand carved. The design of it (despite the comb being highly decorated) is for combing hair and not wearing. Combined with the texture of the stone and even with the polishing my comb has, jade is NOT something I would want my comb to be made of and while it may not ruin your hair, you'd be far better with a horn or carved plastic resin comb.

I don't recommend buying a jade comb unless its carved to be pretty and you only want it to have it, not to use it.

Jade is also very brittle and fragile. It is easy to break.