Is there a way to set bold fonts in xemacs ?

I saw somewhere that in order to change the background or foreground
colour you put in your options file
(set-face-background 'default "black")
or
(set-face-foreground 'default "yellow")

This works but is it possible to use rgb values instead of colour names ?
And how do I learn the full list of colour names available ?

Cheers !