It's not quite the same principle of dentistry, but when they get you to choose teeth for a bridge, you only get a choice of about 12 colours (8 or so of which are going to be obviously way off even before you start holding them up and peering in the mirror). It usually boils down to a choice of 2. It still seems like quite a wide variety, though, so why can't they make veneers in these shades, if they already have the stuff to make actual fake teeth in those colours?