Ah, someone must be watching Diamonique Week!
I have quite a few pieces of Diamonique - I have a strict policy that I never buy my own "real" jewelry (I save that for the spouse! LOL) I have it set in white gold and Epiphany (yes, it's 2 layers of platinum over sterling silver.)
I have never had a problem with the quality of the jewlery from QVC, and my oldest pieces are about 5 years old. Nothing has "turned", rubbed off, gotten cloudy, etc. Now, I have had nothing but problems with my HSN CZ jewelry - Absolute. I don't recommend that at all.