Reward from the Tumerok Banners Quest.
The gem will portal you to one of the 3 casinos depending on which NPC you hand the banner to.
- Lieutenant Kenneth in Cragstone gives Aluvian Gem of Worth
- Shosa Kiroji Matanui in Hebian-To gives Sho Gem of Worth
- Ufet, Prophet of Blades in Zaikhal gives Gharu'ndim Gem of Worth