The agouti group of colors carries the original (wild) color pattern, where the body color comes from hairs that are banded. The tip color is determined by the B and D genes and is black in castors, chocolate in ambers, blue in opals, and lilac in lynxs. Next to it along the same hair shaft should be a red or orange color in the castors and ambers (the redder the better), and a lighter fawn color in the opals and lynxes, all allowing for a bluer hue in the blacks and a browner hue in the chocolates. Farther down the hair shaft is a blue color which should be slate in the castors and opals and much lighter in ambers and lynx. The base is a light dove grey or white. The guard hairs are typically the ones that are tipped. The surface belly color is tan, off-white, or white again, with the dilutes having the lighter colors. The undercolor should be the same as the undercolor of the body.

The second Shading Gene can be c^chd, c^chl, c^h, or c, but not C

The chinchilla gene prevents some of the yellow pigment from forming, leaving the animal looking much like a 'black & white' version of the full color. Since some yellow remains, the midband (and any other parts that would normally be red/yellow) will have a pearl color rather than being white.

In Rex, only the black version of Chinchilla is recognized.

(Black) Chinchilla
Chocolate Chinchilla (Red Squirrel)
Squirrel (Blue Chinchilla)

The second Shading Gene can be c^chl, c^h, or c, but not C or c^chd. The phenotype depends on the second allele because the shaded allele is not fully dominant over the ones below it.

None of these are recognized in Rex. Agouti Cals show the agouti shading which will be most obvious around their nostrils, inside their ears and under their tails.

Black Agouti Cal	Chocolate Agouti Cal

Wild River Rabbitry has a lovely illustrated Shaded Mini Rex Guide.

Judith Graf, Color Basics 1991 (self-published booklet)

Glenna M.Huffmon, The Basics of Color Genetics in Rabbits (I have the 1995 third edition)