Spectrum™

Spectrum™ is a printed security feature developed and trademarked by De La Rue, classified within the iridescent print family. It falls into a broader category of optically variable print effects achieved through the application of special-effect inks — typically containing mica-based or thin-film interference pigments — applied by offset or screen printing over a defined area of the banknote design. When the note is viewed face-on under normal lighting, the element appears as part of the overall design with a characteristic metallic or pearlescent quality. As the note is tilted, the optical properties of the pigment cause the printed element to shift in hue and intensity across the visible colour range, giving the feature its name. This angle-dependent response results from constructive and destructive interference of light within the layered pigment structure — a physical phenomenon that is difficult to replicate accurately with standard commercial printing equipment or inks.

As a Level 1 public-facing security feature, Spectrum™ is designed for immediate first-check authentication by the general public and cash handlers without the need for any tools or special lighting. The colour-shifting response is visually unambiguous when the note is tilted in normal ambient light, making the feature accessible and easy to communicate in public education campaigns. The complexity of the underlying ink chemistry and the requirement for controlled printing conditions provide a meaningful barrier to casual counterfeiting, particularly for offset-based reproductions that lack the necessary pigment formulation and print geometry to reproduce the angular response convincingly.

Spectrum™ functions as a printed-on element rather than a foil-applied or substrate-embedded component, which means it can be incorporated directly into the banknote's printed design layers without requiring a separate application stage. This allows the feature to be integrated into thematic design elements — denomination numerals, national symbols, or background motifs — in a way that contributes to the visual coherence of the note rather than appearing as a discrete add-on. The approach is well-suited to high-denomination and flagship series where design quality and overt visual security are both priorities.

Name

Spectrum™

Category

Security Feature

Effect Types

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Company

De La Rue
Company Website

Product Page

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Linked Features

1 security feature