The Chaucer Review: An Indexed Bibliography (Vols. 1-30)

Doob, Penelope B. R. "Chaucer's 'Corones tweyne' and the Lapidaries. 7 (1972): 85-96.
"Corones" is a different spelling of "ceraunius," a semi-precious stone also named thunderstone. "Tweyne" refers to the two common colors, red and blue, good colors for a lady's eyes and lips. The reference to "corones tweyne" in Troilus and Criseyde suggests that the stones' power will kill Troilus and that Criseyde is to use the stones' power for healing. Though by scorning Troilus Criseyde shows pride, generally punished by a thunderbolt, Criseyde can use her beauty to save Troilus and not draw her punishment. In addition, the colors of the ceraunius fit with references to other gems in the poem.

Taylor, Paul Beekman. "Chaucer's Eye of the Lynx and the Limits of Vision." 28 (1993): 67-77.
Chaucer adds the image of the lynx's eye to his translation of Boethius's Consolation of Philosophy. Jean de Meun also uses the traditional qualities of Lynceus's eyes. Alanus de Insulis's Anticlaudianus and Adam de la Bassée's gloss, as well as the works of Eustache Deschamps, also use this image for sharp sight. Isidore of Seville and John Trevisa's translation of Proprietatibus associate the lynx with the ruby, giving the stone extraordinary healing qualities. Chaucer questions the insight associated with the lynx's eye in the Monk's Tale. Ultimately it becomes a symbol "of the limits of the artist's ability to see and express the perfection of form beneath the ugly matter of things" (75).