Idioms with BLACK

(as) black as a skillet (very black)
My hands were as black as a skillet when I finished working on the car engine.  
as black as a stack of black cats
The little boy was as black as a stack of black cats after playing outside all day.  

coal

pitch

as black as a sweep (very dirty or black. A chimney sweep cleans chimneys and becomes very black)

My friend was as black as a sweep after he finished cleaning the basement.  
as black as coal (very black)
My friend's cat is as black as coal.

as black as night (very dark and black) 

The old house was as black as night when we entered it.

as black as pitch (very black)

 My face was as black as pitch after cleaning the stove all morning.

as black as the ace of spades

The horse in the parade was as black as the ace of spades.

black and blue (bruised)

My shoulder was black and blue after I fell down the stairs.

black and white (either good or bad, either one way or the other way, oversimplified)

Our boss sees everything in black and white.

black box (an electronic device such as a flight recorder that can be removed from an aircraft as a single package)

The investigators searched for a long time in order to find the black box of the airplane.

black eye (a bruise near one's eye which makes it appear black)

The man received a black eye when he bumped into the closed door.

black market (the place where goods or money are illegally bought and sold)

We sold some cigarettes on the black market during our travels.

black out (to darken a room or building by turning off the lights)

During the war, people in the cities were forced to black out their windows so nobody could see them.

black out (to lose consciousness)

The man blacked out during the parade and he had to sit down and rest.

black sheep (of a family) (a person who is a disgrace to a family or group)

The man is the black sheep in his family and has not made a success of his life.

blackball (someone) (to exclude or ostracize someone socially, to reject someone)

The businessman was blackballed in the industry because of his bad business practices.

blacklist (someone) (to exclude or ostracize someone, to write someone's name on a list if they break some rules)

The sports federation blacklisted the swimmer because he was using steroids.

blackmail (someone) (to extort or take money from someone by threatening him or her)

The photographer tried to blackmail the famous actress with some photographs that he had taken.

black-tie event/affair (a formal event where guests wear semi-formal clothes with men wearing black bow ties with tuxedos or dinner jackets)

The award ceremony for the movie awards was a black-tie affair.

in black and white (in writing, officially)

I put down my complaint in black and white.

in (someone's) black books (to be in disgrace or in disfavor with someone)

The boy is in his girlfriend's black books because he was late for their date.

in the black (to be successful or profitable)

Our company has been in the black since they began to cut costs.