The Collaborative International Dictionary of English v.0.48:

Marbleize \Mar"ble*ize\, v. t. [imp. & p. p. Marbleized; p.
   pr. & vb. n. Marbleizing.]
   To stain or grain in imitation of marble; to cover with a
   surface resembling marble; as, to marbleize slate, wood, or
   iron.
   [1913 Webster]

WordNet (r) 3.0 (2006):

marbleize
    v 1: make something look like marble; "marbleize the fireplace"
         [syn: marbleize, marbleise]

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "marbleize":
   band, bar, bespangle, bespeckle, bespot, blotch, check, checker,
   dapple, dot, flake, fleck, freckle, harlequin, iris, maculate,
   marble, motley, mottle, pepper, polychrome, polychromize, rainbow,
   spangle, speck, speckle, splotch, spot, sprinkle, stigmatize,
   stipple, streak, striate, stripe, stud, tattoo, tessellate,
   variegate, vein