A gift is as a precious stone - It both enriches and ornaments. In the latter clause there is an evident allusion to cut stones. Whithersoever you turn them, they reflect the light, are brilliant and beautiful.
A half-satirical description of the power of bribery in palaces and among judges. The precious stone (literally as in the margin) is probably a gem, thought of as a talisman, which, “wherever it turns,” will ensure “prosperity” to him who, being the possessor, has the power to give it.