Obsidian Ioun Stone is an ioun stone which increases Constitution.
This item appears in 
Baldur's Gate II:
Throne of Bhaal (2001)
This icon indicates content from the original Baldur's Gate II: Throne of Bhaal campaign.
Baldur's Gate II: Enhanced Edition – Shadows of Amn (2013)
This icon indicates content from the Shadows of Amn campaign of the Baldur's Gate II: Enhanced Edition.(ToB), it's sold by Karthis al-Hezzar.
Description[]
| “ | The tough obsidian stone imbues its owner with a similar hardiness. | ” |