"Bird Baths" and Reflex/Indents
First the sometimes called "bird bath", but I cannot imagine why until I saw one with a bird perched on the rim, but only once. They are indents with a small glass ball inside, sometimes filled with a liquid, and further decorated with glass sprigs, Dresdner star, tinsel, wire, etc., and resulting in a surprising reflection on the sides of the indent.
The hanging device is sometimes a glass hook on top (funny enough sometimes keeping the pike for a cap), pike with metal cap on top, metal cap at the back which does not give the most delightful result on the tree unless hanging high up.
Largest is dia 6cm, smallest 4,5cm.
Reflex and Indents

Large indent, 13 cm high and 13 cm wide

Comparison: the red is another large indent, 13 x 13 cm. The next one is 10 cm high and the small one 6 cm.