Weird, the Wikipedia book order and the Goodreads order don't match...
https://en.wikipedia.org/wiki/Revelation_Space_universe
https://www.goodreads.com/series/56392-revelation-space
When in doubt I'm heading over to the author's website...
http://www.alastairreynolds.com/novels/
His take on this is: " The reading order isn’t that critical, in my view, but it probably improves things to read REVELATION SPACE, REDEMPTION ARK and ABSOLUTION GAP in that sequence. THE PREFECT (AURORA RISING) and ELYSIUM FIRE may be read alone or jointly, but should best be read in the above order. CHASM CITY, as well as the collections DIAMOND DOGS, TURQUOISE DAYS and GALACTIC NORTH, can be read at any point."