In 628, not long before the date of the Arab invasion, the most precious relic of Christendom, the cross discovered by Helena, mother of Constantine the Great, and believed to be the very cross on which Christ died, was surrendered to the Greek Emperor Heraclius by Kobad II, son of Khusrau II, on the conclusion of a treaty of peace between the Eastern and Sassanian Empires. This cross was one of the sacred objects borne away to Persia from Jerusalem by Khusrau in 615 A.D. It is said to have been guarded carefully through the influence of Sira, Khusrau’s Christian wife. There is a bare possibility that other objects of religious veneration, taken from Jerusalem, may have been given up by the Persians at the same time, and that the unique character of the most important relic so overshadowed all others that historians have failed to note the fact. The cross was restored to Jerusalem by Heraclius in 629, only to fall into the hands of the Mohammedans when that city was taken by the Arabs under Omar, in 637. Hence, if the jewelled breastplate had also been surrendered by Kobad, it would probably have shared the same fate. [Illustration: SILVER CROSS WITH QUARTZ CAT’S EYE. Russian, sixteenth century. Collection of Mrs. Henry Draper.] [Illustration: SPECIMENS OF CHIASTOLITE (LAPIS CRUCIFER). (See page 271.) From the “Metallotheca Vaticana” of Mercatus, Rome, 1719, p. 238. In the author’s library.] We have here a wide field for conjecture,—but, unfortunately, nothing more. Still, in the absence of any definite and trustworthy information, there is a kind of romantic interest in viewing the various possible relations of the mystery surrounding the fate of the most precious gems, historically at least, that have ever existed. More especially is this interest justified in the case of all who are disposed to prize gems and jewels for their symbolic significance, for, as we have shown, this significance, as far as concerns natal stones and the spiritual interpretation of the qualities of the heart and soul symbolized by the color and character of the principal precious and semi-precious stones, has its root in the veneration felt by early Christian writers, beginning with the author of the Apocalypse, for the unforgotten and unforgettable gems that were worn by the Hebrew high-priest.