There are a great many imperfections on polished surfaces, ranging fro
m micro-defects to macro-defects. This report deals with micro-defects
on polished optical glass and a method to reveal them. First, zirconi
a ceramic workpieces and optical glass workpieces were polished. It sh
ould be noted that, they were polished smooth with abrasive powders wi
th superior ability to remove material, but when polished with abrasiv
e powders with inferior ability to remove material the surfaces turned
rough with defects such as digs or pits. It was observed that in glas
s polishing the mechanical actions of large abrasives and dusts do not
make such defects but rather scratch the surface. There was, however,
some possibility that the scratch changed into digs or pits as polish
ing advanced. Then, taking these results into account, a new polishing
condition was proposed using silicone oil instead of the usual abrasi
ve slurry to reveal micro-defects at the surface of glass. For example
, it was shown that there are 10-30 micro-defects in a square millimet
er or 32-165 micro-defects in a cubic millimeter of a dense flint glas
s including cadmium.