Hi Viliam, thank you for your interest in the jewellery Kit! Yes, our jewellery kit is specifically designed to protect jewellery from oxidation and discolouration, significantly extending the longevity of its lustrous shine. This is particularly effective against natural oxidation caused by skin contact, moisture, and exposure to air during wear, offering far superior protection compared to untreated copper jewellery. Under normal wear conditions, the protective effect typically lasts for several years, depending on factors such as frequency of wear, skin composition, exposure to sweat/water/lotions, and maintenance practices. Numerous users report that on frequently worn pieces, this protective layer maintains a like-new polished finish for over two years before beginning to wear off. You may reapply as needed; simply apply directly after cleaning, just as you did for the initial application.