In general, the larger the stone, the more it can amplify the user's "laran". Matrix stones can be used to power aircraft or make a person invisible (The Bloody Sun). Trained matrix mechanics can create a "screen" by placing several jewels within glass in a pattern that they determine on an "ad hoc" basis, depending on the purpose of the screen. This can magnify telepathic powers even more. A screen cannot be managed by a single matrix user. The geological survey conducted The Bloody Sun is accomplished by making and using such a screen; in Sharra's Exile and Two To Conquer, a screen is used to teleport a person from another star system.