According to the Kennel Club breed standard, French Bulldogs should only come in 3 colours: BRINDLE, FAWN, and PIED.
BRINDLE FRENCH BULLDOG
A mixture of BLACK and FAWN hairs and can range from very dark to very light.
Brindle French Bulldogs can have a white chest or other small areas of white. Brindle French Bulldogs have a black nose and dark coloured eyes.
FAWN FRENCH BULLDOG
Clear in appearance and should not have lots of black hairs mixed into the coat.
Very dark fawn colour tends to have a reddish hue and can range from very light to very dark.
Fawn French Bulldogs can have a white chest or other small areas of white. Fawn French Bulldogs have a black nose and dark coloured eyes.
PIED FRENCH BULLDOG
Has a coat that is predominantly WHITE with patches, that can be any of the recognised shades of BRINDLE or FAWN on the head, body or both.
PIED French Bulldogs have a black nose and dark-coloured eyes.
French Bulldogs should NOT be Blue, Lilac, Chocolate, Blue Pied, Blue Fawn, Blue Brindle, Slate, Liver, Black and Tan, Merle.
The only correct colours for French Bulldogs are Brindle, Fawn and Pied. All other colours are undesirable, including solid black, black and white, black and tan, mouse, grey/blue, liver/chocolate.
Any fad, odd or rare colours risk being labelled by the Kennel Club or responsible French Bulldog breed clubs as “Colour Not Recognised”.