I DESCRIBED recently a form of hardness micro-tester which permits light loads to be applied to a diamond indenter of pyramidal form as a means of determining the hardness figures of minute ...

While many of them are certainly not geometric prisms, Wikipedia defines it as a transparent optical element ... tries to exit the glass above a critical angle. Eventually, prism glass was also ...

Scholars knew of diamonds' unrivaled hardness since antiquity, but its unique optical properties went unrecognized ... When light travels through matter - air, water, glass, or diamond, for ...