“Felt tipped” marking pen.

You can also lightly drag the felt tip along the edge from heel to toe with the weight of the pen and feel any imperfection, chips or where the bevels are not meeting. It should glide across the entire edge without snagging.

This will mark both bevels and give you edge feedback at the same time, nondestructively. A Q-tip also works well for this test, easily snagging on any rough spot.

A razor edge is surprisingly fragile, so even if you pass TNT… you have failed by destroying the edge.