I use a 30x loupe. But I only use it for checking for micro chips.
I look at the the edges from the sides at a 90°angle. This allows me to see if the scratches are uniform, and reach completely to the apex. Also, if you have a well lighted wall you'll be able to see the micro chips, by twisting the blade one way or the other till the bevel looks black to the eye, then move up n down the edge with the loupe to see

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