According to the NENZ Encyclopaedia, the cutting edge of a stone or masonry drill bit has a tungsten carbide tip and is usually chisel-shaped. The tungsten carbide adds great durability to the drill bit. The chisel shape gives the drill bit the ability to penetrate further into the stone without becoming blunt too easily.
Thruster
NENZ makes a range of Thruster Percussion Masonry Drill Bits from 1/8 to 1 inch in diameter. The company claims to have the most rigorous testing of all their components. The Thruster has a carbide tip and features a reinforced, ground flute along the drill bit body for effective removal of masonry dust. If Thruster bits become blunt, they can be resharpened to extend their useful life.