Crystal Ground Work of Rock Hardening: The Complete Guide to Floor Crystallization. Crystal ground work (also called floor crystallization or rock hardening) is a professional chemical-mechanical process that creates a hard, crystalline layer on natural stone floors (marble, granite, terrazzo). This layer: Hardens the surface Restores a high-gloss shine Makes the floor more resistant to wear, scratches, and stains It is not a surface coating — it becomes part of the stone itself, delivering longer-lasting protection and easier maintenance.