How to identify the authenticity of a seal?

A seal is the imprint of a seal and a proof of the authenticity of a document. According to article 167 of the Criminal Law, the crime of forging or altering official documents and seals. Identifying the authenticity of seals is a common problem in document inspection. Forged seal printing mainly includes forged seal reprinting and direct forged seal printing. The specific methods of seal are engraving, photographic plate making, digging and splicing, etc. The methods of forging seals include copying mimeograph, drawing, copying, transfer printing, scanning and printing. Due to the difference of pressure, angle, ink amount, gasket and the change of seal itself, it is impossible for the same seal to cover two identical seals. Seal and seal have both correspondence and variability. Therefore, there are two tendencies in printing: one is that the seal is dead, and the seal of the same seal is exactly the same; The other is to exaggerate the possibility of seal change, and rashly interpret the difference of check seal as the result of change, which leads to wrong appraisal conclusion. In recent years, the inspection of seals is much more difficult than before. On the one hand, due to the use of some new materials, such as atomic seals, on the other hand, with the improvement of electronic technology, computer engraving, plate making and scanning are relatively easy, and forged seals are extremely realistic, which can not be recognized by ordinary people only by simple methods such as overlapping and folding corners. However, the magic is one foot high and the road is ten feet high. No matter how forged, there are always loopholes that cannot be solved at all. Handcarved forged seals can't be exactly the same in details such as edges and corners and knife marks. Due to the optical and corrosion principles on which the forged hard printing in photographic plate making is based, it is inevitable that the edges of lines are uneven and the acute angles are dim. It is impossible to find ink with exactly the same characteristics as the real seal in the forged atomic seal in photographic plate making; Because the lowest resolution of the laser head is 0.3mm, it is impossible to engrave the details of the real seal and the edges of the strokes are uneven. The method of directly forging seals is mainly to print with a color printer or copy with a color copier after computer scanning, which is easy to identify under a microscope. There are all kinds of situations encountered in actual case investigation. As long as we have mastered all kinds of forgery methods and their insurmountable defects, as well as the changing law of the seal itself, no Gui Li can escape the eyes of appraisers.