[It's a good thing Bertie went to find an example, because his explanation meant nothing to Boone. He squints at the tie over his shades, then grunts.]

So... dark purple.

[He could be shown an entire range of purples, and he'd probably identify them all as purple. Just some are lighter, some are darker, and some are that annoying colour in between wanting to be purple and another colour, like blue.]