Is it permissible to authorize someone to sell gold, collect the price, and purchase other gold without my presence at the sale?

It is permissible for a person to appoint another to buy and sell what is permissible to be sold, due to the need for it. It is permissible to sell gold for money and buy new gold with it, provided that the exchange takes place in the same session (majlis), and there is no difference whether the owner or their agent takes possession.