In one method, a sieve is suspended from a thread, and a list of names of suspects is read aloud. The person whose name is read when or if the sieve quivers or turns is the perpetrator. (A similar mechanism is used in cleidomancy.)
Another form of coscinomancy is to balance a pair of tongs or shears on the thumbnails or fingernails of two people facing each other. Again, the guilty party's name will cause the shears to quiver or shake.
The relation of these two methods is probably historic, since both were practiced in Athens.