I've never seen one of these Italian blown glass diorama style indent scene Christmas ornaments that wasn't silver on the outside, blue on the inside. This one has a rainbow shaded red, green, and yellow gel tint coloring. I think it's an earlier version of the more common 1950s Italy diorama ornaments.
It measures just over 2 inches diameter. Inside the recessed front opening is a hand painted plastic Father Christmas style Santa figure in with a walking stick and yellow toy sack slung over his shoulder. When held to the light you notice a little inner mercury silvering loss, and the gel paint at the back is crazed (crackled) as shown. No chips, breaks, or damage.
Italy Glass Diorama Scene Indent Christmas Ornament Father Christmas