Look and feel for seams on the plastic.
Feel for an inappropriately light weight.
Check for non-glass lenses.
Look for low-quality metal hinges.
Look for low-quality engravings in the corners of the glasses.
Look for a poor “RB” etching on one of the lenses.
Check the quality of the nose pads.
Check for flushness of the temple logo.
Look for the model number inside the “arms” of the glasses.
Check the box’s label for the glasses’ serial numbers.
Inspect the carrying case for high-quality construction.
Check the booklet for errors.
Look for a high-quality cleaning cloth.
Look for a good-quality lens sticker.
Buy only from licensed retailers.