Here is the description in the Standard of Perfection:
Gray Silkie Bantams (Bearded and Non-Bearded)
Color - Male Plumage
Head
Dark Gray
Neck
Hackle - light gray streaked with darker gray.
Back
Even shade of chinchilla gray.
Saddle
To match hackle.
Tail
Main tail, sickles, and coverts same as back.
Wings
Shoulders, fronts, bows, and coverts same as back.
Primaries slaty gray with center shafting of darker shade.
Secondaries slaty gray.
Breast
Light gray.
Body & Stern
Same as back.
Shanks & Toes
Slaty blue
Undercolor
Smoky gray of a shade not darker than top color.
Color - Female Plumage
Head
Chinchilla Gray
Neck
Hackle - light gray streaked with darker gray.
Back & Cushion
Even shade of chinchilla gray.
Tail
Main tail and coverts same as back.
Wings
Shoulders, fronts, bows, and coverts same as back.
Primaries and secondaries solid even shade of slaty gray.
Breast
Light gray.
Body & Stern
Same as back.
Shanks & Toes
Slaty blue
Undercolor
Smoky gray of a shade not darker than top color.
