Diamond files are made for lampworkers and glass blowers--I think to smooth the sharp parts that occur from breaking off of blowpipes and the like. But these amazing li'l suckers will grind down flash too! Why not? Diamond abrasive is diamond abrasive and it scratches the heck outta glass, whether or not its attached to power source. The only difference between sandblasting and filing is one is powered by squirrels on a treadmill in your basement and the other is powered by YOU! (OK, there's more differences than that, but you get the picture).
I have noticed blue flash files with the smoothest tones. Red is more inclined to be less tonal.
Here's a link to Wale Apparatus who stocks the files. This link should take you to "Judith Schaecther's Preferred File"
But sometimes the links at Wale change so just in case, they call it a"Starpad Deluxe Diamond Rectangular Hand File 2 1/2 inch X 1/4 inch, Item 350085"
I use the roughest grit--120, methinks. The smallest file is 1/4" and you can shape the tip with an exacto or sandpaper for extra insane minute attention to detail...always desirable to the Militant Ornamentalist!
The image above shows the lovely tonal variations possible from filing blue flash. Remember! Sandblast first or your ARMS WILL FALL OFF!!!!!