Several techniques involving X-rays are routinely applied in the study of works of art. These include radiography, X-ray diffraction, and X-ray fluorescence (often coupled with an electron beam instrument such as a scanning electron microscope or microprobe). Radiography provides information on condition and previous restorations or repairs. In the case of sculptures, the technique also sheds light on the manufacturing process; in the case of paintings, otherwise invisible aspects of the painting technique are often revealed. X-ray diffraction is used primarily to provide specific identifications of crystalline inorganic materials, such as pigments, corrosion products, etc. Stand-alone X-ray fluorescence systems provide qualitative or quantitative information on elements in an object or sample. X-ray fluorescence in electron beam instruments provides general elemental composition information, and in some cases is used for quantitative analysis of a wide variety of inorganic materials, including metals, ceramics, glass, stone and paint samples. This analysis also provides microstructural information at the same time. All three procedure can provide important evidence when the authenticity of an artifact has been questioned.