The blue jewel is obtained from Kharshai after completing his miniquest. The blue jewel is obtained by attempting to cut the jewel. Players may continue to interact with the jewel to change its colour. If a player has 90 Prayer, they may search it for curses, which will turn it into a green jewel. If a player attempts to crush the jewel using 90 Strength, the pressure will turn it into a red jewel.
When changed after the miniquest or given to Kharshai to complete it, the Balmung will be upgraded to the Cobalt Balmung.