OCI (OPTICAL CHANGEABLE INK) is by now the most complex
anti-counterfeiting ink with the theory of interference.
The presswork with OCI has gorgeous metal effect and
appears with a pair of colors. Under normal light, it
obviously shows two complete different colors which
vary with the viewing angles, such as Red/Green, Green/Blue,
Golden/Silver etc. This character is unique in inks.
It cannot be reproduced by color copiers or color scanning
apparatus
