Kits of parts comprising a coloring solution, a porous zirconia article, optionally application equipment, the solution comprising cation(s) of coloring agent(s) in an amount above about 0.05 mol/l, solvent(s) for the ion(s), optionally complexing agent(s), optionally thickening agent(s), optionally organic marker substance(s), optionally additive(s), the porous zirconia article showing a N2 adsorption and desorption of isotherm type IV according to IUPAC classification. Methods for coloring a zirconia article comprising the steps of providing a porous zirconia article and a coloring solution, applying the coloring solution to at least a part of the outer surface of the porous zirconia article, optionally drying the porous zirconia article of the preceding step, sintering the porous zirconia article to obtain a colored zirconia ceramic article.