The stone of wisdom

Birth and undeath gems are initially confusing - they do not obey the typical laws one would expect given the way birth and undeath magic are used. Instead, they transmit the substrate of whichever plane they bind to.

Birth

Birth gems are both common and valuable, comparably so to a wedding ring. Most restaurants, churches, and mansions have multiple birth gems. Many households have a very small birth gem, all because of a common conventional use: food enhancement. Birth gems, when activated, imbue rejuvenating properties into anything nearby, be it a person or some common object. Enhanced food provides youthfulness, wellness, and stamina.

Undeath

Undeath gems are deeply coveted, as they safely connect users to the flow of wisdom which permeates the after. The Order of Wisdom is in possession of the largest known undeath stone, and council members use this stone to access an incredible wealth of wisdom from the beyond.

All gems share the property that anyone capable of using magic may use them by directing mana into them. For birth and undeath gems, mana is used immediately for the relevant effect.