Already posted my vote, had some second thoughts. To me it isn't about the color, it's about the substrate used, and its value to the aquarium.
When I was in Hawaii's "Big Island" I visited a beach called "black sand beach" that was essentially covered in volcanic rock, aka pumice, ground up by erosion so finely it made a very comfortable "flooring".
That pumice is the same rock which makes up live rock from Fiji, if it were seeded it could conceivably add as much value to your tank as aragonite, especially if you already have a decent calcium reator or supplementation scheme going.
I'd love to see a tank sometime that uses "black sand" similar to the porous "sand" on that beach. It was quite attractive in its own right.
EDIT: Frankie beat me to it again hahaha.