The Collaborative International Dictionary of English v.0.48:

Inkiness \Ink"i*ness\, n. [From Inky.]
   The state or quality of being inky; blackness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inkiness
    n 1: the quality or state of the achromatic color of least
         lightness (bearing the least resemblance to white) [syn:
         black, blackness, inkiness] [ant: white,
         whiteness]