Tiberius Claudius Nero Germanicus was born in Lyon, France (ancient Lugdunum) in 10 B.C. He was the youngest son of the Emperor Tiberius' brother Drusus and Antonia the Younger, the niece of Augustus and daughter of Marc Antony. Due to poor health and a pronounced stammer, his family assumed that he would never amount to anything. According to Suetonius, even his own mother considered him "a monster, a man whom Mother Nature had begun to work upon but then flung aside." He was not granted any major position during the reigns of Augustus or Tiberius, but in 37 A.D., during the reign of his nephew Caligula, he shared the consulate and presided at the public games in the Emperor's absence. Claudius was possibly involved in the plot to assassinate Caligula, and he succeeded his nephew at the age of 51 as the fourth Emperor of Rome on 24 January 41 A.D. (see Kleiner, Roman Sculpture, pp. 129-134 and Varner, ed., Tyrany & Transformation in Roman Portraiture, p. 114).
According to Varner (op. cit., p. 114) "as a way of visually distinguishing the emperor from his hated predecessor Caligula, Claudius' portraits represent him with relatively realistic facial features, consonant with his age at the time of his accession. Claudius' more realistic portraits would have stood in marked contrast to the youthful images of Caligula, as well as those of Augustus and Tiberius."
The production of Imperial cameos reached an apogee during Claudius' principate, especially in terms of the extraordinary size and quality of the gems produced (see for example, the exceptional Grand Camée de France, in the Bibliothèque National, Paris, now thought Claudian, and the Marriage Cameo in the Kunsthistorisches Museum, Vienna, nos. 126 and 127 in Kleiner, op. cit.). In fact, more Imperial cameos survive from this period than from any other, suggesting that production dramatically increased at this time (see nos. A67-92 in Megow, Kameen von Augustus bis Alexander Severus). Although the Marlborough gem has previously been identified as depicting Tiberius, comparison with other surviving cameos, portraits in the round, and with numismatic evidence, leaves no doubt that Claudius is intended.