Carob Seeds
In ancient times, carob seeds were used to measure gold because they were thought to have a uniform weight. The term "carat" is derived from this convention.
Balance Scales
The balance scales were among the first scales ever invented. They were derived from the principle of the yoke, where two equal masses balance each other if suspended at equal length from a central beam. The object to be measured is placed on one side of a pivoting lever, and weights of known mass are placed on the other to balance. Gold is a heavy metal, and therefore traders would usually weigh it on a balance scale to ensure it was not fake.
Gold Dust Scales
Gold dust was used as currency in certain regions of Africa until the end of the 19th century. The Akan Asante tribe used miniature brass weights to measure quantities of gold dust in Ghana.