Laser etching of gold is being performed by a company called DBC
of New York. They have a process to take photos and put them onto
thin gold discs via laser scribing. The disks are then made into
various forms of jewelry. I have seen the results so I know it
works. They are in the business of selling the etched product not
the process so they would probably not be inclined to share their
technology with you.
However, try contacting David Benderly at DBC at (212) 869 5424
MPI Systems, Inc.