Small micro-mosaic pin with a sepia photo of Pope Pius X (papacy 1903 - 1914). The pin is about 7/8" across , with a floral design and the inscription "ROMA". The setting is brass, with a simple c-clasp on the reverse. I see no missing tesserae, but the photo shows age and the brass has some tarnish.
Mosaics have been a popular souvenir of Italy and the Vatican City since the mid 1800's.