[ridgeguy]

Unknown at present (nobody sells diamond sandpaper yet that I know of), but not likely. Diamond is as bioinert as gold, fluorocarbons, and similar materials in not provoking inflammatory responses when implanted in tissue. Your point about unexpected behavior of dust is a good one. AFAIK, the worst dust hazards (aside from outright chemical or radiological toxicity) are from spiky, acicular particles like asbestos. Diamond dust is either well-formed small crystals or blocky fragments, depending on how it's made. It doesn't exist in needle-like forms that trigger pathological responses from otherwise nontoxic materials.