I agree the colour chooser with the black background at www.bmw.de
makes it look kind of green (which is also not really to my liking).
However the April '07 press release had this to say:
Jerez Black, on the other hand, boasts blue pearl pigments to again provide unique highlights and unprecedented appeal.
So no mention of any green tinges... and my dealer told me it would be similar to Carbon Black (which I liked a great deal).
The virtual dealer at www.bmw.co.za
(car is LHD and has German number plates!) gives you larger images on a white background and it certainly seems more blue than green to me: