Photo Ornament
In American English this is called a "tree-topper". The star is used to represent the Star of Bethlehem that the Magi attached to find the baby Jesus.
Other glassblowers in Lauscha recognised the growing popularity of Christmas baubles and began producing them in a wide area of designs. Soon, the whole of Germany began Photo Ornament buying Christmas glassware from Lauscha and after Queen Victoria's Christmas tree was pictured in a London newspaper decorated with glass ornaments and baubles from Prince Albert's native Germany, Lauscha began exporting its products throughout Europe.
