Fake Nikon filters on Ebay

Word of warning, there are fake Nikon filters on Ebay that are very realistic. The box/instructions are almost perfect and the filter ring is perfectly made, but very slightly thinner (not height). The glass is coated, but where the quality let's it down is in the glass. There's an opaqueness that cannot be cleaned off and will sacrifice image quality. They're rubbish.

So don't be tempted by £20 Nikon filters. If it seems too good to be true, it is.