diamond-coated tools, that are held and used like traditional metal files

These are diamond sharpers, in the format of a metal file, which allows fairly fast but controlled material removal. They're really quite nice.

Benefits:

• cuts in both directions
• works on hard materials (steel that's more than "file hard", carbide, glass, stone)
• lasts a long time

available on the market

• Pferd sells some, but they're exquisitely expensive
• Sharpal — flat, 4.25" tool part — ~ 1" wide — 325 + 1200 grit
• Tarist — flat / round / half-round, 8" tool part — ~ ¾" wide — 120 grit
• Libration — needle file set, both diamond and traditional, 4" tool part — ~ ⅜" wide — unspecified grit
• Drilax — flat set, 3" tool part — ~ ½" wide — range from 40 to 600 grit
• "SE" — needle file set, 3" tool part — ~ ½" wide — range from 40 to 600 grit
• Miracle Diamond Equipment — set of flat tapered, 1" tool part — 2, 4, and 6 mm wide — range from 120 to 600 grit
• Fitool
  • titanium diamond needle files, variety of shapes, 3" tool part — ~ ½" wide — 120 grit
  • black nickel diamond needle files, flat, 3" tool part — ~ ½" wide — 120 grit
• Laser Tools — very fine needle files

Flexible:

• 3M has a whole big range of them
  • at: His Glassworks
  • at: Pack-n-Tape
  • at: Gesswein
  • at: Motion Industries
• IPA — flat, 3.25" tool part - 6 + 9 + 15 mm wide — ? grit [2] [▶]
• Laser Tools

my collection

• Sharpal — flat, 4.25" tool part — ~ 1" wide — 325 + 1200 grit
• Tarist — flat / round / half-round, 8" tool part — ~ ¾" wide — 120 grit