Onyx Gemstone

General
Onyx Gemstones are rare crafting materials. The only known drop location seems to be reward chests in dungeons. But you can acquire one of them as a reward from the quest In the Service of Revenge or you can buy from Rare Material Trade.

Use
Onyx Gemstones are used to craft Destroyer Weapons.

Trivia
The art for Onyx Gemstones was previously used as the icon for the Obsidian Shard prior to the update on Wednesday, 29th of June, 2005.