worth its/one's weight in gold

worth its/one's weight in gold

Extremely valuable; singularly useful. The Roman playwright Plautus was fond of this metaphor, which also appeared in several Middle English works of the early fourteenth century. Somewhat later Henry Medwall (A Goodly Interlude of Nature, ca. 1500) wrote, “Nay ye ar worth thy weyght of gold,” thereby becoming among the first of thousands to use the expression. See also worth one's salt.
See also: gold, weight, worth