I once visited a museum with a wonderful collection of Chinese
carved jade, between 10 AD to 1900's, and that jade, despite being a
6.5 - 7 on the Mohs scale, was extremely durable. Diamonds may the
the hardest substance, but brittle. What stuck in my mind was that a
jade hammer can smash a diamond. Jade is that durable, may be softer
but is one tough mineral and can break diamond. I gained a newfound
respect for the humble jade after that.