When equipped, this item becomes a spirit ruby (a). While worn, whenever the player creates a familiar pouch they have a 30% chance of not using a charm to create it; a charge is used each time it does not consume a charm. Spirit rubies have 30 charges and the item is destroyed once they are all used. Using another spirit ruby on it will consume the inactive one and add its charges to the active one. You can combine up to 990 charges in an active spirit ruby.
Inspecting an active spirit ruby with full charges provides the option to convert it back into an inactive one, so that the player may use it to forge three of them into a Spirit diamond. The net number of charges is 50 fewer, but the chance to not consume a charm is 40% instead of 30%.