Blue river-stones can be crushed into a powder that can make glass look like water.
'We use many materials to make different shades of glass. My favourite colour to make is blue. It is a hard and tricky colour, particularly when you want to make a glass which looks like a flowing river.
'I've only found one thing that can make it look how I like, and that is river-stones the goblins have taken from the Brandywine. Simple, you say, but not so. I tried to gather them myself, but the colour didn't come out the same. Something the goblins must do changes the stone somehow.
'If you can go to Bleakleaf Crest and collect several of the stones from the goblins for me, I would be grateful. I could make the most beautiful tea set you have ever seen.'
Tarnished river-stones can be found in the possession of the goblins at Bleakleaf Crest, south of Dwaling.
Wald Hillburrow has asked you to collect tarnished river-stones the goblins have taken from the Brandywine.
Wald Hillburrow is at Hob Hillbrow's just outside of Dwaling.
Wald Hillburrow will be eager to see the tarnished river-stones that you have collected for him.