1, which distinguishes the color density. The official seal of color printing, its color is very deep, very thick and dense, the tone is very uniform, and the effect of stamping is uneven.

2. Touch the back of the paper. The back of the stamped document paper has a concave-convex feeling, while the color printed paper has no concave-convex feeling.

3. Continuity of handwriting and strokes. The sealed document has coherent handwriting and uninterrupted strokes. Color printed copies will have handwriting and the strokes will be intermittent.