Natural stone manufactures Under the name of natural stone elements may be included several manufactures: from big dimensions objects such as obelisks, fountains, monuments, like other smaller sculptures, bas-reliefs, tombstones, sarcophagus, sacred furniture, aedicule. Even if in the same class of materials, these products can run into problems of conservation also very different, depending mainly on the environment in which they are indoor or outdoor. Therefore a diagnostic test is desirable to assess the conservation status and to plan the restoration, so that it is the most effective and durable.
Among the tests, the most indicate is the accurate observation of the surfaces with a portable optical microscope to determine the conservation state and to identify possible alterations. A correct examination in this sense can be done with reading petrographic thin sections, even with the EIMA software, or with an X-ray diffraction to characterize the degradation products.
For the examination of patinas, whether they are original or result of alterations, the best technique is the FT-IR spectrometry, while for the biological patinas must be performed microbiological tests identifying the species responsible.

Other typical investigations are the ultrasounds to find cracks or discontinuities, the thermovision and the magnetometry to search any pins within the manufacture.

The colorimetry is instead used for the analysis of control during the cleaning.