Well, this cross has probably been done in mosaic tiles made of glass rather than stone. The maker would fabricate long "canes" of glass and then snip off small pieces to us in mosaic work. These things were very popular during the late 19th century when so many people were making the "grand tour" of Europe. A micro mosaic piece showing a Roman ruin or piece of art was one of the best ways to show everyone where you had been without saying "HEY EVERYONE! I was rich enough to make a grand tour of Europe and I even went to ROME!"
This micro mosaic cross is really interesting because it also has a tinted photo of Pope Pius XII in the center! I think it was probably made to commemorate the jubilee year of 1950. I have a similar one showing Pope Pius XI that was done for the jubilee year of 1933. It was clearly made in Rome because the word "ROMA" is spelled out in tiles on the lower arm of the cross.
The framework for the mosaic work is brass twisted wires on the front. The pieces of mosaic glass were carefull set into heavy duty glue and the piece was left to dry. The back of this cross is also brass and the sides have a pretty little dotted detail.
Micro mosaic pieces are fun to collect and some of them can go for thousands of dollars depending on size and the amount of tiles per square inch. The more tiles and the more closely they are set, the better the piece.
