I've been meaning to look into this one for awhile now, and because of a downed phone line I haven't had much internet access these last four days, so this one will be short and sweet.
I didn't even know there was a color called perse until I read the beginning of Adrian McKinty's next novel, I Hear the Sirens in the Street. It's a work in progress, but I'm pretty sure you will still find this sentence if you read the beginning of the book that he has provided for you here:
"The grey snow clouds turned perse and black."
Call me provincial or just call me American, but I had never heard that word perse before. We know it can't mean pink or magenta, but what exactly does it mean?
Google is apparently American enough not to know perse either, because it kept giving me definitions for "per se". Nevertheless, as usual, persistance, or in this case perse-istance pays off and by adding the word "colour" I found that it means a dark, purplish black color, although apprently it used to mean dark blue, or bluish grey. I suppose this last would be one of those fifty shades of grey everyone's on about, a phrase I find somewhat perplexing, but less so now.
The etymology of this word is unclear. It goes back through Old French to Late Latin to persus, which some think is related to a back formation from some form of "Persia." I'm not as interested in where it came from as what it is in this case.
In my hunting it down, I came across a great list of obscure colors which you can find at The Phrontistery , this itself being a great word.
Up until this point in life, though, my only connection to the word perse was that I knew it was the name of a poet, namely, the French poet, Saint-John Perse, aka Alexis Leger. This is not because I am so versed in French poets, quite the contrary, but because he was admired by one of my teachers in this life, Thomas Merton, who besides being a monk and pretty much every other kind of thing you could think of, was also a poet. I was pretty certain of this connection, but I had to track it down for accuracy, and sure enough, Merton starts his essay "Notes for a Philosophy of Solitude" with a quote from him:
"un cri d'oiseau sur les recifs" -- the cry of a bird over the reefs.
With a sky of perse and black overhead, no doubt.