How does Trezza Azzopardi use imagery in The Hiding Place?

Imagery:

"His fingers trip along the stitches, the sharp point of the needle, and down to the cool metal surface of the Biscuit Tin. Then his hand inside, and the unmistakable greasy slip of money beneath his touch. Frankie feels the edges of the notes - not much, enough - catches them up fast and folds them over, straight into his pocket. It takes five seconds."

In the twilight, her own sickness shines like a jewel.