Due to everything that happened to Russia, and the Imperial family during WWI, this egg was never completely finished. It is made of dark blue glass, engraved with the star constellation of the day of Tsarevich Alexei Nikolaevich's birth - the Leo sign. The stars are marked by rose-cut diamonds, and the cloud-shaped base is made out of opaque rock crystal.
Inside the egg was a clock mechanism. The clockwork and the dial - which was to be placed around the egg like a ring around a planet - are missing though, together with most of the diamond stars.
The "Constellation Egg" was long thought to be missing, but was found in 2001 at the Fersman Mineralogical Museum in Moscow.