use for cutting metals or hard objects
It helps underpaid service staff make ends meet and it can also serve as a reward for good product or service.
One use is in top-of-the-line phonographs (record players); diamond, being the hardest mineral known to man, won't skip or wear down as the needle traverses the grooves of the album.
you need a device called action replay or AKA AR
People use diamond-tipped engravers or lasers.