Cracking Slabs - Look Out Below

I don't crack often, my buddy does though. Vise and hack saw in the garage.

If we crack, we always check the coins out intensively, sunlight, shaded light, 20-40x binocular microscope, before cracking just to make sure the grade is => the TPG's.

A couple of weeks ago a Mexico 1 P went under the saw. It looked nice, under graded perhaps. Out of the plastic, naked eye, hairlines were obvious, even more so under magnification. Keep in mind that two experienced students of numismatics examined the coin in TPG holder for at least 20 minutes, the lines were not visible through the plastic, and I have a good eye.

Next cut, a couple days ago, Cundinamarca 8 R, typical Indian and pomegranate weak strike, but the sharpness of the lettering had it at least 10 points ahead of TPG grade and we checked it out. Out of the plastic, raw this looked ok, still +10. But an acetone treatment (24 hrs., 5 mins., rinse) revealed small scratches. Can't really complain about this because they were not visible without the gunk removed.

Point is: plastic hides flaws even with a good microscope that should be able to focus to the surface of the coin.

One coin was NGC and the other I think was PCGS.