Can't help with your request exactly, but if you look in the 51 book - page 67 - you will see colour comparisons between UK burgundy, plum and USA dark burgundy - allegedly under bright lighting. It makes you think that there couldn't ever be a mistake over plum, but of course that doesn't take into account the vagaries of individual pc screens, and ageing eyes.
I know that when I've looked at grey on ebay, it sometimes appears green, but then there are some not too good photographers there who probably wouldn't know a quality photo if it jumped up and bit them.
I could imagine that a poor quality picture of plum and cordovan might be confusing.
Edited by PaulS, 15 November 2016 - 17:20.