My last substrate was coral sand that I double bleached but as you say, it's not really white.I agree with @MagicJ i used it for years on freshy and salty tanks, size was always 00 or 000 (really fine). That would have to be the whitest sub i've seen.
Most aragonite/crushed coral tends to be an off white .. I did bleach my crushed coral sub for my current tank, it did come out whiter than I expected but still not white white. HTH
Did you have much trouble with it blowing around?I used crushed marble for 10 years without any issues. I can't remember what grade it was but the grain size was very similar to normal coral sand.
They only reason I'm not still using it is that it had a lot of larger shells mixed in with it (left over from a former plenum system) and I couldn't be bothered trying to sift them all out.