From Diablo Wiki
Legendary Gems were added to Reaper of Souls in Patch 2.1. They can only be socketed in jewelry, only used by characters (not Followers), only drop from Greater Rift Guardians and can only be upgraded via Urshi. Each gem can be upgraded to Rank 50, and the maximum level unlocks a special extra bonus property.
See the Legendary Gems article for full details, or the specific gem pages for more details on each.
Pages in category "Legendary Gems"
The following 14 pages are in this category, out of 14 total.