A scale ... for what ?

[Richard G]

Fernando, like yourself, I'm only speculating, but if the counterweight can be moved further out from the fulcrum, and held there by placing the washer against the bar then you could weigh ounces, grams, or whatever. For example if you were to put an ounce weight in the tray, then adjust the counterweight until it is in equilibrium you would know anything subsequently put in the tray weighs an ounce. .This may have been useful to persuade customers etc, they were not being fiddled. Similarly, say for 100 grms
Initially, I thought these had a "western" look about them but now I'm not so sure. I can't see any reason why they should not be for weighing gold, but I presume could also have been used for other relatively high value materials, pearls, cosmetics, perfumes, spices, drugs (!), even tobacco etc.
Regards
Richard