King spent much time in
Italy, where he laid the foundation of his collection of
engraved gems and
gemstones, which, having been increased by subsequent purchases in
London, was sold by him in consequence of his failing eyesight, and was presented in 1881 to the
Metropolitan Museum of Art,
New York. He was recognized universally as one of the greatest authorities in this department of art. His chief works on the subject are: •
Antique Gems, their Origin, Uses and Value (1860), a complete and exhaustive treatise •
The Natural History of Precious Stones and Gems and of the Precious Metals (1865) •
Early Christian Numismatics (1873) •
The Handbook of Engraved Gems (2nd ed., 1885) •
The Gnostics and their Remains (2nd ed. by
J Jacobs, 1887, which led to an animated correspondence in the
Athenaeum) == Classicist ==