Is it permissible to rent out gold and silver jewelry for a fee, or are they considered like currencies, making such an act usury (riba)?

Renting jewelry for money is permissible. It falls under the category of ijarah (definition) (leasing/renting) and is not subject to riba (usury/interest). Imam Ahmad explicitly stated its permissibility, and this view was also held by Al-Thawri, Al-Shafi'i, Ishaq, Abu Thawr, and the Hanafis (Ahl al-Ra'y). Al-Mawardi stated that riba does not apply to a contract of ijarah. The Permanent Committee (for Islamic Research and Fatwas) permitted renting jewelry for either of the two currencies (gold or silver) or other forms of payment, for a known rent and a known duration, with the permissibility of taking a pledge (collateral) for it.