Clearly not, since the police took the knife because it looked much cleaner than the other knives and, so they say, smelled strongly of bleach. I had a look at my kitchen knives. None of them are "notably" clean. They have water marks on them for example. In my kitchen draw a knife that was shining like a mirror would certainly be notable.
The honest answer is that I don't know what the material was, or if it existed. Perugia-shock claimed that this material was reported in court. As far as I'm aware Perugia-shock is the only source for this claim:
http://perugia-shock.blogspot.com/2009/05/lab-of-wonders.html
Having said that, I don't see that it would server their editorial line to make it up.