An elven stone is a magical artifact capable of long distance conversations.
Furthermore, the elven stone does not require magic in order to operate and it can be used by people who do not possess magical powers.
The blood mage Frenic gives an elven stone to Knight-Commander Martel in order to communicate and coordinate their actions. It is implied that Frenic has a similar stone as well.
While chasing Cassandra Pentaghast and Regalyan, the Knight-Commander uses the elven stone to send a message to Frenic, and a few moments later he receives an answer. However by that time he loses the stone to Regalyan who after a fierce fight manages to escape along with Cassandra.The two of them reach the Seekers of Truth headquarters outside Val Royeaux and inform Lord Seeker Aldren of the Knight-Commander's betrayal. The Lord Seeker also receives the elven stone in order to use it as evidence however a few moments later he is killed by Martel who takes the elven stone back into his possession.
- If Dorian Pavus and the Inquisitor are friends or in romantic relationship during the events of the Exalted Council he will give them a "sending crystal" in order to communicate with each other after he returns to Tevinter. While it cannot be verified that this is an elven stone, Tevinter has a history of appropriating ancient elven magical techniques and artifacts.
- According to Patrick Weekes in an ROT13 coded tweet, if Dorian and The Iron Bull are in a romantic relationship, Bull also receives a sending crystal from him, though not directly stated in the game.