Garden Of Cassia by Gabrielle Wang

Mimi lives with her parents above her father's herbalist shop. She hates being Chinese and being teased at school. More than anything she loves to draw, so when her art teacher gives her a box of pastels Mimi is thrilled. These are no ordinary pastels for the inscription on the box warns that they are "A treasure for some, a curse for others". Mimi is able to draw amazing scenes on the footpath outside her father's shop and the pastels breathe life into the pictures for those able to see it. When Gemma, her tormentor at school, steals the pastels, Mimi knows she must get them back - not only to keep them safe and their magic intact, but to save Gemma from the pastel's curse.