It cannot be valued with the gold of Ophir. The locality of Ophir has been much contested, but, on the whole, the weight of evidence would seem to be in favour of Arabia, on the south-east coast (see the article on "Ophir" in Smith's 'Dict.
of the Bible,' which exhausts all that can be said on the subject). The high estimation in which "gold of Ophir" was held appears not only in this passage, but also in Job 22:24; Psalms 45:9 : and Isaiah 13:12.
It is to be accounted for by the imperfection of all the anciently known processes of refining, which left the best refined gold inferior to the natural product of the Ophir mines or washings. With the precious onyx, or the sapphire.
(On the latter of these two stones, see the comment upon Isaiah 13:6.) The "onyx" is probably the stone now known as the "sardonyx," which was highly prized by the ancients. It had a place in the breastplate of the high priest (Exodus 28:20), and is mentioned among the treasures of the King of Tyre (Ezekiel 28:13).
The sardonyx presents layers variously coloured, as blue, black, white, and vermilion.