She very carefully carves the runes into bead. It's rather difficult because of it's size. She points the staff at it, and wills the spell to life.
The runes glow, as does the bead but…
Because the bead is smaller, the light it produces is also a lot less bright. At most it might light up a book she's holding nearby. She'll need a bigger thing to hang off her neck, or she'll have to rethink how she does this altogether.