Crystals

Red
"Thanks to Michael's recent lessons in crystals as amplifiers of sigilcraft... Crystals of this color (Red) were a lure, useful in the construction of traps." Bk 2, ch 49

A beacon with this much red crystal can out-ply any dragon (within range).

Pink

Yellow

Blue

Clear

Songs
here

Crystal-adepts
Kyrie

Lapis

Other dragons?