וְשַׂמְתִּ֤י כַּֽדְכֹד֙ שִׁמְשֹׁתַ֔יִךְ וּשְׁעָרַ֖יִךְ לְאַבְנֵ֣י אֶקְדָּ֑ח וְכָל־גְּבוּלֵ֖ךְ לְאַבְנֵי־חֵֽפֶץ׃
Je te construirai des créneaux en pur cristal, des portes en escarboucles, et toutes tes barrières seront en pierres précieuses.
Rashi on Isaiah
jasper Heb. כַּדְכֹד, a kind of precious stone.
Malbim on Isaiah
Kadkhod is the gemstone called Shoham, according to the Sages.
Ibn Ezra on Isaiah
כדכד Agates. It is hap. leg.; it is the name of a precious stone.