What is an ocean star?

The Star of the Sea, one of the four giant gems in the imperial court of Mongolia, is said to be used for divination and sky observation. Its origin is unknown, but one of its sources was plundered from a small Slavic country during the "eldest son's Western Expedition". The texture of the gem is blue, about the size of a seal. Its birthplace is Laitan (now Nogundi area in western Pakistan). It is said that after being driven to the north of the Great Wall by Zhu Yuanzhang, the Mongolian Empire was lost during the migration of Mongolian nobles, and its whereabouts are still unknown. Some people claimed that when the Germans captured Kiev in World War II, they saw the Ocean Star in the underground vault of the Soviet National Bank, but it was not confirmed. In the middle of the sea in the movie Titanic is based on the real diamond of doom "Hope".