The invention relates to a coloring solution for coloring a dental ceramic article, the solution comprising: a solvent and a coloring agent, comprising rare earth element metals or ions being present in the solution in an amount of at least about 0.05 mol/1 solvent and transition metals or ions being present in the solution in an amount of about 0.00001 to about 0.05 mol/1 solvent. The invention also relates to a process for coloring dental ceramic articles, dental ceramic articles treated either with the coloring solution or obtainable by a process comprising the step of firing the dental ceramic articles.