C. W. King was born on 4 September 1818 at Newport in Monmouthshire and entered Trinity College in 1836. He graduated with first class honours in the Classical Tripos of 1840 and was elected a Fellow of Trinity in 1842. He remained a Fellow all his life and lived in College for most of that time, except for the period 1845–50, which he spent chiefly in Italy.
During his residence on the continent King was able to pursue various antiquarian interests, in particular the study of engraved gems which was to occupy him for the rest of his life. He began to acquire examples of such work, and by a series of judicious purchases over the following years he formed an important collection of Greek, Roman and other early gems. Towards the end of his life he sold the collection. It is now in the Metropolitan Museum of Art in New York.
Returning from Italy in 1850, King adopted a quiet existence at Trinity, publishing a number of works on antiquarian subjects, including Antique Gems (1850), Handbook of Engraved Gems (1866, 1885), and Early Christian Numismatics and other Antiquarian Tracts (1873), besides many papers contributed to joirnals and learned societies. He also wrote on The Gnostics and their Remains (1864) and translated works of classical literature such as Plutarch's Morals (1882). Although he took no part in College teaching or administration, King was by no means reclusive; he formed longstanding friendships both at Trinity and elsewhere, and was often consulted as an authority by the gem collectors his works had helped to inspire.
In later years King was troubled with failing eyesight, and he was obliged to give up the detailed close work his collecting demanded. But he continued to study and write, and was in regular correspondence until shortly before his death, which occurred after a short illness on 25 March 1888.