Clean with warm soapy water followed by rinsing with clean water and drying with a soft cloth. All finishes are vulnerable to acid attack and some strong substances such as household cleaners or disinfectants can cause surfaces to go black or peel.
https://www.cphart.co.uk/look-tumbler-and-holder/LOB1602CPLook Tumbler and Holder//www.cphart.co.uk//images/products/medium/LOB1602CP.jpg152.15152.15GBPInStock/tumblers/LOB1602CP