synthetic single crystal quartz

Dear labmembers, does anyone have used synthetic single crystal quartz
before, either as wafers or for other functionality? I am hoping to find
very tiny amount (~mg) of quartz for use in high-pressure measurements.
I was wondering if you happen to have old samples that you'll never use
again containing quartz? Or if you know where to get synthetic single
crystal quartz. I'd really appreciate any kind of help.

Thanks and happy holidays!
Shibing Wang
shibingw@stanford.edu