Boyd’s Bible Dictionary:
(gold stone). Evidently the yellow topaz (Rev. 21:20).
Concise Bible Dictionary:
Probably the ancient topaz of a golden color (Rev. 21:20). The Greek word χρυσόλιθος occurs in the LXX in Exodus 28:20; Exodus 36:20; Exodus 39:13 and Ezekiel 28:13.
Topaz
Jackson’s Dictionary of Scripture Proper Names:
gold-stone