There is gold, and a multitude of rubies. For peninim, which is rendered "rubies," "pearls," or "coral," see on Proverbs 3:15. There is gold which is precious, and there is abundance of pearls which are still more valuable.
But the lips of knowledge are a precious jewel, and worth more than all. We had the expression, "lips of knowledge," in Proverbs 14:7; it means lips that utter wisdom. Keli, often translated "jewel" in the Authorized Version, also boars the meaning of "vessel," "utensil."
So here the Vulgate, vas pretiosum; and the wise man's lips are called a vessel because they contain and distribute the wisdom that is within. (On the excellence and value of wisdom, see Proverbs 3:14, etc; Proverbs 8:11, etc.
) Connecting this with the preceding verse, we are led to the thought of buying, and the Lord's parable of the merchant seeking goodly pearls, and bartering all his wealth to gain possession of a worthy jewel (Matthew 13:45, etc.
).