Claudia has her great-grandfather's red hair and her great-grandmother's gold eyes. She is depicted wearing a summer dress.
Like her great-grandfather, Claudia is a solipsist; she believes that the world has been hers since she was born--therefore, if she wants something to happen she will find a way to make it so. Firo (who acts like her uncle or godfather) notes that while many of Claire's descendents have adopted his way of thinking, Claudia is the most like him even at the age of fourteen.
(To be added)