Sending Stones

Wondrous Item, minor uncommon

Sending stones come in pairs, with each smooth stone carved to match the other so the pairing is easily recognized. While you touch one stone, you can use an action to cast the sending spell from it. The target is the bearer of the other stone. If no creature bears the other stone, you know that fact as soon as you use the stone and don't cast the spell.

The emblem has 3 charges. Each time sending is cast through the stones, it expends 1 charge. The stones regain all expended charges daily at dawn. If one of the stones in a pair is destroyed, the other one becomes nonmagical.

Source: Dungeon Master's Guide, p. 199