For more than a thousand years, since before the time of Dolure the Abstruse, natural philosophers have sought the Common Tongue -- that mythical linguistic wonder that would bind together all peoples. It must exist, reasoned many, simply because it would make things so much easier. Alas, many a treatise later, the world has still not seen this elusive efficiency, despite several attempts to create one with alleged divine inspiration.
In the meantime, people from different lands who wished to communicate with each other simply languished without communication... no, wait. That's not right. Practical people devised all manner
of solutions from the basic (if time-intensive) expedience of simply learning other languages to magical workarounds. Of the latter, none has been more useful, nor lead to bloodier wars than the touchstone.
All participants in a conversation must remain in contact with the stone during a conversation. This is usually accomplished by sitting across from one another and touching one's fingertips to the stone. Vessuna
will sometimes use their tails instead, as they tend to talk with their hands.
Arcane apprentices get sick of churning out touchstones, but it is a large part of their "training." It does, it must be said, ingrain some ritual habits that later allow their attention to be focused on more important things in the course of working more complex spells.
Polished stones are preferred, but not required. Any old rock will do. As a related aside, some communities far from urban centers will have a large "meeting stone" at the boundary of the village rather than individual touchstones. There they invite outsiders to come and talk to an elder or leader, often with both hands pressed flat against the stone between them as a show of peaceful intent.