Molten star-glass

Molten star-glass is used during the Across The Sky quest to make a Star-glass orb. From there, it must be enchanted and blessed in order to make an Orb of life.

Simply smelting the star-glass gives 25 Crafting and Prayer experience, while blowing the molten glass into an orb gives an additional 175 Crafting and Prayer experience, for a total of 200 experience each.

After the quest, one may create the Molten star-glass again and blow it into Star-glass orbs for more experience, however they can no longer be imbued or blessed. They can, however, be enchanted like normal Uncharged orbs and attached to battlestaves. Doing so provide no additional benefits to the resulting battlestaff.