This authentic cobalt blue kugel glass Christmas ornament was made in Germany in the late 1800s. It's quite large in size and heavy, over 4-3/4 inches diameter (closer to 5 inches high due to the slightly domed top) with a circumference of 15 inches. I've shown a normal size coffee mug in the last photo for scale.
Kugels are colored within the glass, not painted or finished on the outside, and the mercury silvering is on the inside. The ornament has magnificent deep cobalt coloring and excellent mirroring. There's a bull's eye circle of inner mercury degradation on one side, shown in the third photo. The glass kugel itself has no damage. There are a number of tiny bubbles in the mercury or glass, very common.
The veined five leaf type brass cap will slide a bit when pushed but is very secure. For being well over 100 years old, the kugel is in wonderful condition. The blue color is actually darker than most of the photos show.