Speaking of God and his dealings with mankind, Proverbs 16:11 says: “The just indicator and scales belong to Jehovah; all the stone weights of the bag are his work.” (Other versions) Yes, both the scales and marker (the "just indicator") and every stone in God's bag is just, fair and right in his dealings with mankind. Likewise, we ought to have a “complete stone-weight” in our dealings with others. (Proverbs 11:1. Other versions)
Understanding what this meant was common to adults back when Proverbs was written. But today, most people only encounter scales in grocery stores and hospitals. In stores, they are either electronic (built into most register scanners) or in bulk and produce departments. Essentially, the stones were probably the predecessors of weights we use on some scales. I don’t know what form of checks-and-balances were used to verify a valid stone-weight back then. Perhaps there was one stone held as the “standard” and merchants brought their stones to try to match against that standard as close as possible. (There were other means of deceptive weighing besides using incorrectly weighted stones. This article merely considers stones because of the scriptural reference.)
Overall, the main concept being conveyed is fairness in our dealings with others. Impartiality and truthfulness are necessary in our treatment of others in order to receive God’s approval.