The Collaborative International Dictionary of English v.0.48:

Lazuli \Laz"u*li\, n. [F. & NL. lapis lazuli, LL. lazulus,
   lazurius, lazur from the same Oriental source as E. azure.
   See Azure.] (Min.)
   A mineral of a fine azure-blue color, usually in small
   rounded masses. It is essentially a silicate of alumina,
   lime, and soda, with some sodium sulphide, is often marked by
   yellow spots or veins of sulphide of iron, and is much valued
   for ornamental work. Called also lapis lazuli, and
   Armenian stone.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lazuli
    n 1: an azure blue semiprecious stone [syn: lapis lazuli,
         lazuli]