Is it permissible to take money in exchange for pawning something valuable, then return the money with an increase upon redeeming the pawn? And is that considered usury (riba)?

It is permissible for the debtor to give the creditor a pledge from his valuable possessions as security for the repayment of the debt. Scholars have agreed that pledging is permissible. It is not permissible for the creditor to demand more than what he lent, because every loan that draws a benefit is forbidden usury (riba).