I've used Nature's Own brand, black aragonite live sand and I love it. Makes the colors pop on everything. Just had to rinse it very well in saltwater water first.
I've used the Carib Sea Hawaii black sand in a nano previously. I thought it was a cool, interesting look and its not magnetic. You do see detritus more easily in my opinion so will need some sifters or the ability to siphon the bed periodically.
I have the Hawaiian black and I can confirm it is not ferrous and does not attract to magnets.
The actnic lights are what give the "blue" look. That would be a lighting choice, nothing to do with the sand.
I'm my picture the day lights and actnic are both on. If I turned the day lights off it would be the "blue" water you are looking for.
Oh ok thank youthe sand does look great, i think it will make bright colors Pop nicely