What is this symbol / logo that appears on Italian lighting?  

well, an image search for the logo didn't turn up anything decipherable other than a reference to Schuko plugs which are widely used in all of Europe. But when I started looking at different arrangements of the letters M, I, and Q, I got somewhere. It's some kind of certification for electrical plugs, probably something to do with safety. IMQ is the order of the letters. It doesn't appear to have anything to do with the designer or manufacturer of a given lamp or fixture.

http://www.imq.it/en/chi_siamo/index.html

tk got it. it is an electrical safety conformity mark. It means that the component is certified to IEC standards, or prior to IEC, it would have been a country specific standard like DIN, BS, AFNOR, etc. Akin to the UL mark on US products.

Thanks a lot, you've cracked it @spanky/tktoo/Zephyr - I've only ever seen this on Italian lighting so probably safe to say it proves country of provenance at the very least. Be well and thanks again!