Ruby

[Jewel] Can be used to craft a sapphire, or sold to a shop for gold.

[Source]
Alchemy (Jewels)
Ghillieglade
Heaven's Arena
Pit of Petrax
Guardian Legion Jewel Box

Kelsaik's Treasure Crate Sea Chest Kumas Toybox Battle Reward Corsairs' Chest Monarch's Treasure Chest Prince's Treasure Chest Zenith Treasure Chest +72