Well, the etching looks right, though that can be faked. The thickness, shape, curve, and bevel do also. That's no 100% guarantee, I have some lenses I'm sure are aftermarket which match shape, thickness, curve, and bevel perfectly. However, I guess that's as close to certain as you can be without holding them in your hands and checking the optics, unless somebody can spot a problem I haven't seen. The lens coating also seems to match, for what it's worth. Seems like most aftermarket lenses of that type go for a more solidly mirrored finish (accomplished with a film rather than a finish).