Satraajit was a devotee of the sun god. Although he adored Surya, he treated the sun god as if he were a close friend. Pleased with his devotee, Surya bestows the Syamantaka gem on him. When Satrajit entered Dwaraka after his worship, wearing the gem, he could not be identified as the splendour made him look like the sun. People report to Krishna that Surya was coming to visit him. Krishna laughed and tells them: "It is not the sun god. It is only Satrajit glowing with his gem."
Satrajit consecrated his residence and installed the gem in a suitable place. The unique quality of the gem was that, if worshipped properly, it would yield daily, a good quantity of gold, besides protecting the worshipper from famine and other calamities, mental worries, bodily ailments and other evils. Krishna sought the wonderful gem to handed over to the King Ugrasena (as it would protect the whole kingdom). But Satrajit, covetous of wealth, refused to part with it - unable to portend the consequences.
Prasena, the brother of Satrajit went hunting, wearing that lustrous gem on his neck. A lion killed Prasena and his horse due to the uncommon glow of the gem and snatched it away. While entering its den along with the gem, the lion was killed by Jambavan, the glorious bear (of the Ramayana). He used it as a plaything for his boy.
Satrajit felt miserable when his brother did not return back from the hunt. He told his people, "Surely my brother, who had gone to the forest with the jewel, has been killed by Krishna." The people then began spreading that malicious rumour, which soon reaches the ears of Krishna. In order to wipe out the imputation cast on him, Krishna follows on the tracks of Prasena's horse along with some citizens of Dwaraka. They find the remains of Prasena and his horse in the forest, and the tracks further on lead them to the dead lion and finally to the Jambavan's cave.
Krishna asks the people to stay outside and entered the dark and fearful cave alone. He saw the self-effulgent gem being used as a plaything beside a child and waits there, resolving to take it away. The nurse who looked after the child, shrieks. Jambavan rushes in and engages in a combat with Krishna. A powerful wrestler that he was, Jambavan fought Krishna fiercely with a mace. Then with trees, rocks, bare arms and fists. A tumultous duel ensued between the two, continuing for days together. The lightning fast strokes of Krishna pounded Jambavan, depleting his courage and strength considerably. Jambavan had not experienced such discomfiture anytime in his long past. Perspiring all over, he speaks to Krishna: "I conclude you to be none other than Vishnu. You are the same Lord Rama, my master, who subdued the arrogance of the sea and built a bridge over it, and slayed the rakshasas." Krishna compassionately pats his devotee Jambavan with his soothing hand: "It is for the sake of this gem that we arrived at this cave, O Chief of bears! I have come to wipe out a false imputation cast on me through this gem." Jambavan joyfully gave away the gem to Krishna and also his daughter Jambavati, as a way of worship.
The people outside the cave waited for twelve days and finding that Krishna did not return, went back to Dwaraka in despair. Devaki, Vasudeva, Rukmini and other relatives also grieve. The people of Dwaraka curse Satrajit and worship Goddess Durga, the supreme energy of the Lord, for the safe return of Krishna.
Krishna gladdens the hearts of all the people making an appearance in Dwaraka with his new bride Jambavati and the Syamantaka gem.
Krishna summons Satrajit into the royal presence at court and tells him how the gem was recovered. He then hands over the gem to Satrajit. His head bent in shame, Satrajit repents for having spread calumny about Krishna, and returns home with the gem.
In order to remedy his reputation as being covetous of wealth and mean-minded, he decides to give away to Krishna, the Syamantaka gem and also his daughter Satyabhama, who was gifted with comely looks, magnanimity and other virtues. Krishna's marriage to Satyabhama was performed according to tradition. But
Krishna refuses to accept the gem. "Let it remain with you, O devotee of the sun god! We shall only enjoy the fruits of that gem."