Modify a font colour that has no colour name

[jonetsu <jonetsu@teksavvy.com>]

Doing C-u C-x = on a org mode link shows the face that's used.
Although the colour of the face turns out not to be a colour but a
name, 'link'.  If a colour is put in this field, the links disappear so
to say, and no colour is applied.  Is there a way to change the colour
of that face and is it possible to do it only for the links in org mode
(although I do not mind if all links everywhere are adopting the same
colour) ?

Thanks.