Luster is a blush, but is normally used a highlighter on deeper skin tones. That's because the bronze peach color just melts into our skin and the gold shimmer in the blush remains visible. The shimmer is not chunky like in Angelika or Super Orgasm, which I don't like. It's also not like Whisper of Gilt or Superb at all, which I also love.
Luster is a very soft, natural, gorgeous highlight on darker skin. It'll work beautifully into the natural and neutral looks that you like to do.
EDIT: I just noticed your new location.