Numismática Diamantino is a Lisbon-based numismatic retailer serving collectors and customers interested in precious metals. The company offers coins and banknotes from Portugal, its former colonies, Europe and around the world, alongside gold and silver bullion bars. Its catalogue spans historic and modern pieces, commemorative issues, proof and uncirculated editions, and themed releases featuring subjects such as wildlife, sport, art and popular culture. Gold coins and investment pieces, including sovereigns and bullion coins, are also available.

Beyond collectibles, Numismática Diamantino supplies specialist equipment and accessories for coin and stamp collecting. Its range includes albums, holders, capsules, catalogues, books, scales, magnifiers, cleaning products, tweezers, gloves, trays, cases and safes. The website also provides coin values and quotations, precious-metal calculators covering gold, silver, palladium and platinum, and information about Portuguese hallmarking marks. Customers wishing to sell coins can contact the business or arrange an appointment. Numismática Diamantino also directs visitors to Diamantino Leilões, its auction service, reflecting a tradition it describes as drawing on three generations of knowledge.