At the risk of being a boring old fart, what is wrong with plain old Maroon? Just thinking if you give it a more fancy name it confuses people and it could be worth more trouble in the end.. But if you want a fancier name you could go with
Burgundy
Dark ruby
Deep plum
Sienna Red
Indian Red
Or go with some grape names LOL Merlot..
Good luck with whatever you go with..
Dark Venetian Red