there are all kinds of browns in the rabbit world, and oddly enough, none of them are called brown!
So well said. Chocolate as a stand-alone color refers only to the non-agouti (solid self-colored rabbit) with the brown recessive
(bb) instead of the dominant black
BB or
Bb. Rabbits with other color patterns that still have the brown recessive
bb may have the word 'chocolate' in their name. A castor/chestnut agouti with brown instead of black is a
chocolate agouti (also called cinnamon). A tortoiseshell with brown instead of black is a
chocolate tort. A pointed white with chocolate instead of black is a
chocolate Himalayan (or Himi for short)/ chocolate Californian/ chocolate pointed white depending on breed. You get the idea.
These are all colors on the dominant full-color 'C' gene, either
CC or
C with something more recessive. The C gene actually has five color choices, called 'alleles'. Full color
C- is the most dominant. All the colors more recessive to that have more and more of the pigment removed from the fiber. Next down in dominance is chinchilla, coded
c(chd) for chinchilla-dark.
Chinchilla removes the fawn band from the fiber, so a chestnut agouti, which normally has a fawn middle band and some fawn mixed into the outer color to make it look brown, now is a gray chinchilla with pearly white in the middle band. The really silly one is when you mix chinchilla with a fawn agouti. Fawn non-extension
ee removes all the dark color from the hairshaft, only leaving the yellow shades. Chinchilla removes the yellow. So you end up with a pearly white rabbit with dark eyes, called
ermine.
Your
sable is the next down in dominance. Sable not only removes all the yellow/fawn/red colors, it also leaches out some of the dark color. So deep black becomes a dark sepia brown, like an old photograph. Genetically, it's still black, still has the
BB or
Bb black alleles, but the sable allele, coded
c(chl) for chinchilla-light, has removed enough of the dark color to render it sepia instead of black.
There are two more alleles more recessive than sable, one is the
Himalayan/Californian/pointed white gene, coded
c(h) for Himalayan. Here, all of the color is removed from the main coat and eyes, with color only remaining on the points (nose, ears, tail, feet), the most extreme (and therefore coldest) points of the body. Himi is a cold-sensitive pattern, only making color where the body is cooler. The most recessive color is
albino red-eyed-white (also called ruby-eyed-white, or REW for short.) This rabbit can genetically be any pattern at all, but the recessive
cc allele turns off the pigment producing cells, so it can't wear the colors it is genetically programmed for. Which is why it is sometimes called a rabbit wearing a white sheet, you can't see what genetic colors are hiding beneath the white exterior.
So, this is how you can end up with brown shades that aren't chocolate.