What color do crystal grams display under UV light on E passports?

Crystal grams, which are a form of security feature incorporated into e-passports, are designed to enhance the passport's authenticity and deter counterfeiting. When viewed under UV (ultraviolet) light, these crystal grams exhibit a rainbow effect. This characteristic is intentional, as it adds a layer of complexity and security to the passport. The rainbow appearance helps verify the document's legitimacy, as it is difficult to replicate accurately with standard printing technologies used by counterfeiters.

Other colors mentioned, such as blue, red, or gold, do not accurately represent the documented appearance of crystal grams under UV light, thus reinforcing the uniqueness of the rainbow effect as a distinguishing feature of genuine e-passports.