The Collaborative International Dictionary of English v.0.48:

Dactyliology \Dac*tyl`i*ol"o*gy\, n. [Gr. dakty`lios finger ring
   + -logy.] (Fine Arts)
   (a) That branch of arch[ae]ology which has to do with gem
       engraving.
   (b) That branch of arch[ae]ology which has to do with finger
       rings.
       [1913 Webster]