Gummi stones come in three grits, but do you think I could find what the equivilent numbers are? - nope.
Color - use -(guess at grit)
Coarse (Grey) - edge cleaning, deburring the edges. - (600 or 800)
Red (Fine) - fine buffing of edges. A few strokes will shine an edge. Also harder than the grey. - (1000)
Tan (Extra Fine) - For super fine buffing of edges. Leaves a mirror finish. - (2000)
(2000 grit sandpaper used wet will give a mirror finish on metal)
Think polishing, not sanding.