"In his first edition of The Giaour he had used this word as a trisyllable—'Bright as the gem of Giamschid'—but on my remarking to him, upon the authority of Richardson's Persian Dictionary, that this was incorrect, he altered it to 'Bright as the ruby of Giamschid.' On seeing this, however, I wrote to him, 'that, as the comparison of his heroine's eye to a "ruby" might unluckily call up the idea of its being bloodshot, he had better change the line to "Bright as the jewel of Giamschid;"' which he accordingly did in the following edition"
(Moore).
In the
Sháh Námeh
, Giamschid is the fourth sovereign of the ancient Persians, and ruled seven hundred years. His jewel was a green chrysolite, the reflection of which gives to the sky its blue-green colour. Byron probably changed to "ruby" on the authority of
Vathek
(p. 58, ed. 1856), where Beckford writes,
"Then all the riches this place contains, as well as the carbuncle of Giamschid, shall be hers."