a star sapphire

Cut in a cabochon, this deep blue gemstone displays a blue-white, six-rayed star in its middle. Unless kept in total darkness, the star seems to shine as bright as Helluin in a clear night.

It is a star sapphire.
It weighs a couple of ounces.

You identify a star sapphire.
It weighs two ounces, and it is worth about forty lauren.
Its keywords are sapphire, star, jewel, and gem.