I see that the King's exchanger can get me from glass to blood seals. Is there another NPC that can get me from blood to diamond seals?

Or, a way to go from BP to diamond?

The King's Champion: into the caverns. Go into Brim, speak to Anataeus. Next step unclear. Said to seek him at viking camp in SI. Cannot find him there -- assuming SW Gywd. Now journal text is garbled anyway.