Depending on charging grit, it is used for CUTTING, PREPOLISHING, or POLISHING with diamond. For polishing, it is usually used for the harder stones, 7 or above. Other than cast iron, it is the hardest metal commonly in use, furnishing flat facets and crisp meets.
This laminated lap has a full 3 mm thick 100 Electrolytic Tough Pitch copper bonded to our standard 1/4″ Aluminum baseplate, and then diamond-turned on both sides for flatness. There is sufficient metal to allow for many resurfacings over the lifetime of the lap (And user.)

Gearloose has discontinued these laps. One in stock here.