Gemma's matrilineal great-grandmother, born Jean Specterman, was Jewish (of Polish Jewish descent). The rest of Gemma's ancestry is English, with more distant German and Scottish.
During her time as a student at the Royal Academy of Dramatic Art in London she worked as a make-up salesgirl.
Was born with an extra finger on each hand, a benign condition known as polydactyly, and had the extra digits removed as an infant. The scars from the surgery are virtually unnoticeable today.
Were filming her last scene for A Deal Is a Deal (2008) when she was told, she had won the part in Quantum of Solace (2008).
Was in consideration for the role of Eliza Doolittle in My Fair Lady after Keira Knightley dropped out of the project, but Carey Mulligan was cast instead.