black as Newgate's knocker vs dusky

black as Newgate's knocker

• Completely black in colour. 

dusky

• Having a shade of color that is rather dark. 

• Ashen; having a greyish skin coloration. 

• Dimly lit, as at dusk (evening). 

• A dusky dolphin. 

• A dusky grouse. 

• A dusky shark.