First of all, be reminded that lime scale occurs when the washbasin isn’t maintained regularly.  We advise to dry up dark coloured bathroom fixture (basalt, marble) after use. Part of the sediment can be removed by polishing the whole surface with steel wool grade 000 damped with BO CIM. Repeat application until the result is visible. Rinse with clean water between each application and once the basin is completely dry, seal the surface with BO Protect or BO Protect +.