Only the following colours have their names specified in ste standards and therefore these are the only ones guaranteed to work when you use their names: aqua, black, blue, fuchsia, gray, grey, green, lime, maroon, navy, olive, purple, red, silver, teal, white, and yellow.
There are another 130 that will usually work - see
http://www.crockford.com/wrrrld/color.html