It appears to be fine quality pocket ... watch crystal which would have been visible in the center. I do not have the watch and I suspect this dial was salvaged from it during the great gold ...
In November, an 18k gold pocket watch, a gift from survivors of the Titanic to the captain of the R.M.S. Carpathia, which rescued them, was acquired at auction in the U.K. for $1.97 million ...