"with a tortoise-shell clasp"

A tortoiseshell ornament of Micronesia.
GNU Free Documentation LicenseA tortoiseshell ornament of Micronesia. - Credit: Maksim
Tortoiseshell Cat
Creative Commons Attribution Share AlikeTortoiseshell Cat - Credit: DrL
Grandmamma’s handbag has a tortoise-shell clasp. In this instance it is likely a synthetic tortoise-shell, i.e. a substance made to resemble the actual shell of a tortoise. The term is also used to describe cats with colouring in shades of brown, black and cream.