Sterling silver, 22K gold, boulder opal.  Look at the galaxies in these stones!  Boulder opals are always a favorite, but I can't find many I like any more. I have been saving these for just the right earring!  2-3/8" long from the post by 1-1/4" wide.
(Please look at the close up photo, there is a small pocket that is naturally occuring in the stone). 
Exchanges only please.