Corynebacterium diphtheria produce black or grey colonies on the following agar
Corynebacterium produce black or grey colonies on potassium tellurite blood agar It acts as a selective medium for its growth Ref: Textbook of Microbiology Baveja 5th ed Pg 211
Mac-conkey agar
Potassium tellurite agar
Thayer main medium
Tinsdale agar
Bacteriology