A false balance is abomination to the LORD: but a just weight is his delight. A false balance is abomination - This refers to the balance itself deceitfully constructed, so that it is sooner turned at one end than at the other. This is occasioned by one end of the beam being longer than the other.
But a just weight - אבן שלמה eben shelemah, the perfect stone probably because weights were first made of stone; see the law, Deuteronomy 25:13-16 (note).