Engraving on hard surfaces without cutting into the metal
The picture below displays a golf putter engraved with a black mark, burned into the metal. The engraving is black and does not effect the precision of the golf club, yet it is permanent.
(The font used for the 3 initials RHL is Century Gothic)
Below is a Cuisinard steel kitchen knife engraved in monotype corsiva font.
The picture below (slightly out of focus) represents a heated black mark engraving