Calsier's Alerter

A large yellow gemstone the size of calsier's fist shown in the center glowing even more brightly than the walls that gem was surrounded by a lattice of golden metal holding it in place. The arse arcanum mentions in way of kings that that is specifically a fabriel called an alerter and can warn of a nearby object feeling sensation or phenomenon we're guessing on either what spren is trapped or how it's it's settings basically.