The seal is the imprint of the seal and is the proof of the authenticity of the document. According to Article 167 of the Criminal Law, it is a crime to forge or alter official documents or seals. Identifying the authenticity of seal seals is a common problem encountered in document inspection. Forged seals and seals mainly include forged seals and then stamped and directly forged seals. The specific methods of seals include engraving, photoengraving, patching and splicing, etc.; the methods of forging seals include mimeographing, drawing, copying, transfer, scanning and printing, etc. Due to differences in pressure, angle, ink volume, backing materials and changes in the seal itself when stamping, it is impossible for the same seal to produce two identical seals. Seals and seals have both correspondence and variability. Therefore, there are two tendencies to avoid when inspecting seal inscriptions: one is to think that seals are dead and think that the same seal will produce the same inscriptions; the other is to exaggerate the possibility of seal inscriptions changing and put the difference between the inscriptions being inspected Differences are rashly interpreted as the result of changes, leading to erroneous identification conclusions. In recent years, the inspection of seal seals has been much more difficult than before. On the one hand, it is due to the use of some new materials that vary greatly, such as atomic seals. On the other hand, with the improvement of electronic technology, computer engraving, plate making and scanning are relatively easy. The forged seals are extremely lifelike and cannot be recognized by ordinary people by simple methods such as overlapping and folding corners. However, the magic is as high as the Dao. No matter how you forge it, there are always loopholes that cannot be solved at all. For hand-engraved forged seals, the edges, corners, knife marks and other detailed features cannot be exactly the same; for photo-engraved forged hard seals, due to the optical and corrosion principles based on their manufacturing, uneven lines and edges will inevitably appear. Acute angles are blunted and other phenomena; it is impossible to find ink with the same properties as the real seal for forged atomic seals made by photographic platemaking; for forged seals produced by electronic engraving machines, since the minimum resolution of the laser head is 0.3mm, it is not only impossible to engrave the real seal Detailed features, and the edges of the strokes are jagged. The main method of directly forging seals is to scan and process it with a computer and then print it with a color printer or copy it with a color copier. It can be easily identified by observation under a microscope. There are all kinds of situations encountered in actual prosecutions. As long as we are proficient in various forgery methods and their insurmountable flaws, as well as the changing rules of the seal itself, no Li Gui can escape the eyes of the appraiser.