What's More Precious Than Rubies, More Lasting Than Gold

Riddle: What's more precious than rubies, more lasting than gold, what can never be traded stolen, or sold, what comes with great effort, takes time but then once yours will serve you again and again?

Answer: Knowledge.

Source: https://www.riddles.com/index.php/7954

What's more precious than rubies, more lasting than gold, what can never be traded stolen, or sold, what comes with great effort, takes time but then once yours will serve you again and again? — What's more precious than rubies, more lasting than gold by LilyABC v1.

Riddle: What's more precious than rubies, more lasting than gold, what can never be traded stolen, or sold, what comes with great effort, takes time but then once yours will serve you again and again? Answer: Knowledge. — by LilyABC v2.