This is not a colour;
magenta a.k.a "pink" does not appear on the spectrum and yet we see it! Why?
UPDATE: Apparently some of the graphic guy's here at work have taken issue with this, it may well all be a conspiracy ...
Also, some feel magenta is blend of blue and red.
UPDATE 2: this link sheds more light on the issue:
The truth is, no color actually exists outside of our brain's perception of it
[The] article might be better titled, "Magenta is not a single wavelength of electromagnetic radiation in the 'visible' spectrum, but our brain perceives it anyway."