Note 1447 — ULTRAMARINE.

Plin. Inutiles scalpturæ, intervenientibus crystallinis centris.—Several learned men have understood this passage as if Pliny said that the sapphire could not be cut; but they seem not to have attended properly to the author’s words, and to have forgot what the ancient artists called centra in stones and different kinds of wood which were to be cut. This Pliny himself explains, b. xvi. c. 39. In b. xxxvii. c. 2, he reckons also “prædurum ac fragile centrum” among the faults of rock crystal, which however, when it had not this blemish, was very proper for being cut. Theophrastus uses in the same sense the word κέντρον.