As the other reviewer has commented, Swarovski's "black" pearl color is not a true black but rather a very dark grey. ("Mystic black" is true black, but therefore lacks the pearly finish -- mystic black is shiny, but not "pearly.")
I was aware of this ahead of time from reading reviews (thanks, reviewers!), so for me these were exactly as expected. I also purchased a Tierracast charm in their "black" finish (which is also more of a very dark grey or gunmetal), and these matched perfectly, which is what I was hoping.
As for the quality, well, these are Swarovski pearls, so (in my experience) they are pretty much flawless, except for maybe a handful in every 100 or so.