Ruby

The ruby appears in the wisdom literature and the prophets as the standard against which other valuables are measured. The recurring use is comparative: wisdom, a worthy woman, the lips of knowledge, and the nobles of Zion are all set against rubies and graded by them.

Wisdom Above Rubies

Job's hymn on wisdom prices it past every gem and metal, ruby included. "No mention will be made of coral or of crystal: Yes, the price of wisdom is above rubies" (Job 28:18). The verse stands inside a longer comparison that also names onyx, sapphire, gold, glass, jewels, coral, crystal, and the topaz of Ethiopia — wisdom outranks the entire gem-roster.

Proverbs reuses the same comparison-shape. "There is gold, and abundance of rubies; But the lips of knowledge are a precious jewel" (Pr 20:15). Gold and rubies are paired as the inventory of obvious wealth, and the lips of knowledge are graded above them as the rarer jewel.

The Worthy Woman

The closing acrostic of Proverbs 31 prices the worthy woman by the same standard. "A worthy woman who can find? For her price is far above rubies" (Pr 31:10). The valuation-formula is the wisdom-formula transferred to a person — the woman's worth set above the gem.

Zion's Ruddied Nobles

Lamentations turns the ruby's red into a description of Zion's former nobility, before their fall. "Her nobles were purer than snow, they were whiter than milk; They were more ruddy in body than rubies, their polishing was as of sapphire" (Lam 4:7). The four-fold whiteness-to-redness comparison sets snow, milk, ruby, and sapphire against the bodies and polish of the nobles, and the ruby supplies the ruddiness term.