Revival stones for dressing sintered diamond engraving wheels are available in grits ranging from 80K (coarsest) to 220I (finest), are used to revive and shape diamond and polyurethane tools, extending their lifespan and preventing chipping.

Specifically:
80K for diamond tools of 150-300 µm (35-80 grid mesh)
150I for diamond tools of 45-150 µm (80-500 grid mesh)
220I for diamond tools of 1-45 µm (500+ grid mesh)