I remember watching a documentary about a man who would marry (multiple) women, then steal their money and leave.

one of the victims said she had doubted the ring he gave her was real, but he just scratched a mirror with it to prove it was real. Then she said "it was only later after he left that I found cz can also scratch glass"

I just looked it up and CZ is harder than glass, so disregard what I said above!