This is a so-called “Single lip engraving router bit” with a Polycrystalline cutting edge.
Polycrystalline tools can be named also PCD (Synthetic Polycrystalline Diamond) tools and they are tools for working granite and hard material.
These granite engraving tools have 10 mm cylindrical shank and are holed, so they allow inner water flow.
A Polycrystalline CNC engraving tool is often used by marble-carvers for engraving black-granite headstones, for granite tombstone writing, and for hard-stone monuments reliefs.
The performance and wear mechanisms of polycrystalline diamond (PCD) engraving tools have been investigated in a lot of tests in granite and hard natural stone. The experimental results indicate that PCD performance has a greater thermal wear resistance at high cutting speeds. Results show that the dominant wear mechanisms for PCD is abrasion wear but a Polycrystalline engraving tool in granite lasts up to 10 times longer than Widia router bit.