Eyes of Golorr

The Eyes of Golorr are small round marble-like objects of unknown properties, sought by many factions within waterdeep, including the Zhentarim and the Xanathar Guild at the least.
Three Eyes exist. 
One has been found in the Brandath Crypt, rescued from the clutches of Devils by the Harpers.
Another was stolen by the Zhentarim from a locket carried unknowingly by Renaer Neverember.
The third is unknown.