At this morning’s Crafting Sanctuary panel, the D3 team gave some additional details surrounding the gem system. Here’s a link to the new gem levels table: Gem Levels
Blizzard has previously mentioned that only 5 levels of gems will drop in the world. To get a gem to the 14th level (Radiant Star) will be quite an undertaking. It will take a total of 19, 683 gems to get from level 5 to level 14. Mind-boggling.