Sergio Giovine

Sergio Giovine is an illustrator for American Girl, primarily creating the cover art for the Historical Character Mysteries.

Caroline Abbott

 * Traitor in the Shipyard

Cécile Rey and Marie-Grace Gardner

 * The Hidden Gold
 * The Cameo Necklace
 * The Haunted Opera

Rebecca Rubin

 * The Crystal Ball

Julie Albright

 * The Silver Guitar
 * Lost in the City

Trivia

 * On Sergio Giovine's website, there is an image titled "Ceyenna: American Girl Portrait Study" that bears similarities to how Cécile is illustrated on the cover of The Cameo Necklace. It is quite possible he was considered for illustrating Marie-Grace and Cécile's Central Series.