FFS Coloccini is miles better than David Luiz and has been playing in his prime for the last 2 and a half years. He only just turned 30 and has a good 4 years left in him and he will be much better and much much cheaper than David Luiz.
Luiz definitely has the potential to be as good as Coloccini , it is clear to see that they are very very similar players (No not because of the hair) who extremely comfortable on the ball technically. Coloccini is just far better adapted to the English football than Luiz I guess, along with being the better player.