From Guild Wars Wiki
Darkstone Chests are locked chests found throughout the Ring of Fire Islands region and may be opened using a Darkstone key. Opening a Darkstone chest adds one point to the Treasure Hunter title for the character.
- Using a lockpick, a Darkstone Chest has a 30% base retention rate.
- Opening a Darkstone Chest adds one point to the Treasure Hunter title.
- Darkstone Chests drop gold items at a much lower rate than high-end chests from other campaigns.