Buff blacktail

Color and pattern male

Plumage: uniformly warm golden yellow, except for the black pattern on the primary- and secondary-flights and the black tail feathers; a few small black feather tips are permitted at the lower neck-hackle, but they should not degenerate into a greater black tip.

Primary-flights: black with a uniformly warm golden yellow edge, which should be sharp and not too broad.

Secondary-flights: black with a broad, uniformly warm golden yellow edge on the inner vane; the outer vane is a uniformly warm golden yellow, so that when the wing is closed, it is almost entirely a uniformly warm golden yellow.

Tail: steering-feathers black, sickles black with evenly warm golden-yellow edging and light shafts; in contrast, most males have such a wide warm golden-yellow edging on the shorter sickles that they are predominantly golden-yellow.

Down: light salmon or gray, however a gray down color should not penetrate the upper color.

Serious faults

Golden-yellow patches on the tail steering- feathers. Absence of black on the wing-flights. Black feather tips at the lower neck-hackle or a distinct striped pattern. Uneven, much too light or too dark color. White in any part of the plumage.

Faults

Slightly too much golden-yellow in the large sickles. Insufficient pattern on the wing-flights. Slightly uneven color. Slightly too light or slightly too dark in color.

Color and pattern female 

Plumage:  uniformly warm golden yellow, except for the black tail steering-feathers; the black pattern on the wing-flights are similar to those of the male. A few small black feather tips, which must not degenerate into a greater black feather tip, are permitted at the lower neck-hackle.

Tail: steering-feathers black,  except the top feathers on each side on either side, which must have a narrow, sharply defined, uniformly warm golden yellow edging; a narrow, uniformly warm golden yellow edging on the other tail feathers is permitted. Coverts black with a narrow, uniformly warm golden yellow edging; completely golden yellow tail coverts are permitted.

Down: Light salmon or gray, but gray down color should not penetrate the top color.

Note

The male is generally a darker yellow than the female.

Serious faults

Golden yellow patches on the tail steering-feathers. Absence of black in the wing-flights. Black feather tips at the lower neck-hackle or a distinct striped pattern. Uneven, much too light or too dark color. White in any part of the plumage.

Faults

Too broad golden yellow edging on the tail steering-feathers. Insufficient pattern on the wing-flights. Slightly uneven color. Slightly too light or slightly too dark color.

Genetic code: https://kippenjungle.nl/Overzicht.htm

Website with all available information regarding chicken genetics including the chicken color calculator.