Something I saw demonstrated by a gem appraiser who specialized in
jade:
Jade is such an efficient conductor of heat that you can tie a human
hair tightly around a piece of jade, play a cigarrette lighter flame
on the hair,and it will not burn.
I have seen this demonstrated and have done it myself. It works. Not
as destructive as attempting to scratch the piece with a knife.
Lee Einer
Dos Manos Jewelry
http://www.dosmanosjewelry.com