וְשַׂמְתִּ֤י כַּֽדְכֹד֙ שִׁמְשֹׁתַ֔יִךְ וּשְׁעָרַ֖יִךְ לְאַבְנֵ֣י אֶקְדָּ֑ח וְכָל־גְּבוּלֵ֖ךְ לְאַבְנֵי־חֵֽפֶץ׃
And I will make thy pinnacles of rubies, and thy gates of carbuncles, and all thy border of precious stones.
Read Jewish philosophy on Isaiah 54:12: Rambam's Guide for the Perplexed, Saadia Gaon, and classical Jewish philosophical sources, free online.