1. A "hidden" number "100" can be seen when the 100-yuan note is viewed horizontally at eye level. On a fake 100-yuan bill, the number can be read at all angles.

2. You can feel the ridges on a genuine 100-yuan bill, especially to the right of the bill beside the large image of Chairman Mao (above). Fake 100-yuan bills do not have ridges.

3. When the note is held up against the light, the security thread runs continuously from top to bottom in a solid line. Fakes have gaps in the lines. (See photo below)

4. Held against the light, the two halves form the shape of a Chinese coin. On the left of the Chinese coin, the watermark image of Chairman Mao should be distinct when held up against the light.

5. A watermark showing the number 100 is translucent when held up against the light. Some fakes have none.

6. The number 100 (above) is printed using colour-shifting ink that changes from green to blue on a real 100-yuan bill.

- Zaihan Mohd Yusof

This article was first published in The New Paper on Jan 18, 2009.