The most valuable gemstone with
sweet fragrance found in Kshira Sagara "-the ocean
milk" , where Lord Vishnu resides. The name means a Divine
Jewel worn by lord Vishnu. It is believed in the Hindu scriptures to be the most valuable ratnam in the whole
world and a symbol of divine authority.
In Hindu Mythology, the Devas and Asuras performed the "Churning of the Ocean of
Milk" (Samudra manthan), in order to
get Amrita. In this process, the fourteen treasure jewels (Ratnas) emerged from the ocean. The fourth Ratna that emerged is known as Kaustubha. It represents pure consciousness shining in all its luminous manifestations. It was
said by Lord Shiva that nobody in the universe except Lord Vishnu could handle the brilliance and magnificence of this "Mani", since it could corrupt the bearer by infusing in them with a greed to carry it forever.
Kaustubhadhari is the person who is wearing that Mani i.e. Lord Vishnu.