In French all nouns are either feminine or masculine.
Noun gender does not stand alone but enters into a complex relationship with adjectives
and word order, all of which reinforce gender marking in French. Colors in French act just as
adjectives do and agree with the noun they modify. How ever there are certain colors that remain
unchanged.
Here you will see both groups: les couleurs variables et les couleurs invariables.
Colors are always placed after the noun they modify: une femme blonde, un homme brun