Unlike the five ordinary charms, obsidian charms are unstackable, similar to abyssal charms, as they are tertiary ingredients, and will also require an ordinary charm when making pouches. However, as they are still considered charms, the triple charm bonus from Familiarisation increases the quantity of obsidian charms gained per drop, and they can be collected by a charming imp. Turning obsidian charms into the charming imp instead yields 6 experience each. Like other charms, they are also untradeable.
Familiars that can be made with the obsidian charm are: