Colours in French are adjectives. They are placed after the noun they describe. So a blue sky is “un ciel bleu.” They must also agree in number and gender with the noun they describe. So “purple flowers” would be “des fleurs violettes.”

Colour	Masculine	Feminine
black	noir	noire
white	blanc	blanche
red	rouge	rouge
blue	bleu	bleue
yellow	jaune	jaune
orange	orange	orange
green	vert	verte
purple	violet	violette
pink	rose	rose
brown	marron	marron (yes, this is correct)
grey	gris	grise

Dark & light colours

If you want to describe a colour as “dark” or “light,” add “foncé” (dark) or “clair” after the name of the colour. These two words must also agree in number and gender with the noun they describe. So a light blue sky would be “un ciel bleu clair,” while dark purple flowers would be “des fleurs violettes foncées.”

Bluish, whitish, reddish

If you want to describe something as “reddish” rather than “red,” you add the suffix “-âtre” to the colour name. Some of the names change, while others ignore the rule completely, so here is a list:

Colour	Masculine	Feminine
blackish	noirâtre	noirâtre
whitish	blanchâtre	blanchâtre
reddish	rougeâtre	rougeâtre
blueish	bleuâtre	bleuâtre
yellowish	jaunâtre	jaunâtre
orangish	orangé, orangeâtre	orangée, orangeâtre
greenish	verdâtre	verdâtre
purplish	violacé	violacée
pinkish	rosâtre	rosâtre
brownish	brunâtre	brunâtre
greyish	grisâtre	grisâtre