Possible Clues:

• Makes the picture blacker with 'Sulphur and hell go together'
• Sunglasses, to the hip
• Slangy sunglasses for literary ghosts
• Coulourful shell?
• Ultimately efficacious underworld disguise, sometimes
• Cats may wear them?
• Sunglasses - ghosts
• Modern sunglasses or old ghosts
• Nicholson wears them
• Colours or ghosts