There are tri-colored ferrets that are white, brown and black.  Usually
these are a silver mitt (black mitt, roan mitt or other variant on the
name) that has brown areas.  I've seen a lot of mitts that have leanings
this way with out having a real defineable brown patch.  My tri-color hob
is a medium silver (roan mitt) with a definite brown triangle with its
base along the strnum and extending around the body until it ends at a
point right back at the sternum.  Yes I'm going to try to reproduce
tri-colors through breeding as this hob is amazingly healthy and the
other best example I knew (Georgia Bailey's Bootlegger) was as well.  I
wouldn't reproduce the pattern if it appeared to be linked to any major
genetic flaws.
 
You didn't mention white feet though so I don't think this is the case here.
 
Many Sables that appear blackish also have brown in them.  I'm trying to
track the shades of sables to see if there is a way to genetically track
them.  You didn't say how dark the brown was.  If it is really dark than
it is not uncommon in Sables.  If it is really milk chocolate colored I'm
at a loss.
 
Unfortunately you also didn't mention enough about the pattern to call it.
You said the legs were black and the body I think is rather lighter
especially given the description of the head so I'd probably guess a Sable
Siamese or Sable Point (dark legs with substanially darker legs and tail).
 
Kind of hard sometimes without seeing the ferret.
 
bill and diane killian
zen and the art of ferrets
[Posted in FML issue 1404]