Base colour black is simply black on the E
or extension gene. Black is dominant to chestnut so EE is black, Ee is
black and ee is chestnut. All horses will be one of these three
combinations. This gene can tested for and the test can be used to see if a
black based horse carries chestnut and also to identify black based horses
that have been diluted or modified to an extent that it is no longer
obvious what their base colour is.
Black foals are usually born anything from a silver grey
colour to a mousy brown. Most colours are much better assessed once the
foal has lost their first foal coat.
All these pictures are of black based horses however
most if not all will have some other genes at work as well. I tried to find
pictures of black based gypsy horses with minimum effect from other colour
patterns and modifiers. Quite tricky!! Donations of photos welcomed!