Cool it, breaking point BASED ON PRESSURE will decrease, at the lowest possible temperature, 0.1 pressure could even break it.
I don't know if the other way works if you heat it up, it's breaking point would increase.
The breaking point does increase substantially, but it's not enough to protect it from stuff like DMG, which produces basically infinite pressure change.
Quartz breaks like glass, it's pressure change that destroys it (since its original function allows it to conduct electricity from METL when under high pressure.)
When it's extremely hot, it's actually -more- resistant to breaking, which serves one of its original purposes as an all-around unbreakable element.