The engraved stone in the ring is a table-cut sapphire, the monarch being figured standing, with a nimbus around his head; he is crowned and bears a sceptre. The letters S L on the stone have been interpreted to mean rather _sigillum Ludovici_ than _Sanctus Ludovicus_, and one critic suggests the possibility that it may have been executed in Constantinople, in Byzantine times, for Louis VII, who was there in 1147, and was received with high honors by Manuel Comnenus, the Greek emperor’s courtesy being rather bred of fear of French aggression than of affection for the French crusader. As we have good evidence that gem-cutting was not practised at this time in France, it seems plausible enough that Louis VII should have availed himself of this opportunity to have a signet engraved for him by a Greek gem-cutter.[253] The signet ring of King Charles V of France (1337–1380) was set with an Oriental ruby on which was engraved “the bearded head of a king.” This signet was used by King Charles to seal the letters written by his own hand. The somewhat vague description in the inventory suggests that this may have been an antique gem, the supposedly royal head being that of some Greek divinity. The art of engraving on such hard stones as the ruby does not seem to have been practised in the thirteenth or fourteenth centuries, the revival of this art belonging to a later period. Evidently the head was not that of Charles himself or of any of his predecessors, for, had this been the case the inventory would hardly fail to note the fact.[254] When a certain Bratilos was sent as a messenger by the eastern emperor Cantacuzene (1341–1355) to his empress Irene, to announce the outbreak of a dangerous revolt, he bore a sealed letter from the emperor.[255] While on his journey, however, he began to fear that he might be waylaid and robbed of the important document. This peril he effectively provided against by memorizing the letter and then destroying it, after he had removed the wax impression of the imperial signet, which he could safely guard in his mouth, and which served to accredit him when he came before the empress.[256] Not long afterward Cantacuzene was defeated and deposed by John V, Palæologus, and retired to a monastery, where he lived until 1411, composing a history of his own times in his leisure moments; his wife also took the religious vows under the name of Eugenia.