Common traits of all horses with a basic colour chestnut

Chestnuts have no black pigment, they only have red pigments; these come in a great variety of shades.

• The coat can be any variation of brown (pale yellow/red to dark brown). 
• Mane and tail can be any variation of brown (pale yellow/red to dark brown), but are never much darker than the coat colour.
• The limbs are the same colour as the rest of the coat.

Genetics

Possible gene combinations: AAee, Aaee, aaee.

There must never be an E gene – in its absence, there is only red pigment, the A gene has no effect as it only controls the black pigment.

Shades of chestnut

• Light chestnut: coat is light brown (yellowish or reddish), mane and tail are the same or lighter.
• Golden chestnut (Sorrel in American): coat is orange-red with a metallic sheen, mane and tail are the same or slightly darker.
• Dark chestnut: coat is dark reddish-brown, mane and tail are the same.
• Liver chestnut: coat is dark coffee brown, sometimes almost black with a reddish hue, mane and tail are the same, sometimes bleached slightly at the tips. 
• Chestnut with flaxen mane and tail: coat a shade of chestnut (from light to dark), mane and tail several nuances lighter (yellowish to cream) – this is presumably a genetic modification.