Bulino engraving actually cuts away a small amount of metal, usually in the shape of a diamond. These diamonds are very small- kind of like dots. The reason for cutting away the small pieces of metal is that if you do it correctly then you won't leave a bur on the surface (or it will be very minimal). If you use a round pointy tool and drive it into the metal it does not cut the metal away. It only displaces the metal and pushes up a bur around the "hole" like a crater rim. This crater rim over time will wear at an accelerated pace and become shiny which will detract from the engraving.