GST on optical elements designated at standard rate, effective later in September, with exclusions for unworked glass and intraocular lenses. Lenses, prisms, mirrors and other optical elements mounted or supplied as parts of or fittings for instruments or apparatus are taxable at GST 18% effective 22-09-2025, excluding glass not optically worked and intraocular lenses, pursuant to Notification No. 9/2025-Integrated Tax (Rate).