Optically Variable Ink (OVI)
Definition
An ink containing thin-film interference flakes (metal + dielectric layers, manufactured by SICPA and others) that produce a visible colour shift with viewing angle, used on denomination numerals of high-value notes including the Indian ₹500, US $100, EUR €50, and GBP £20.
- Color shift range
- Green to blue on Indian ₹500 and ₹2000 notes
- Mechanism
- Thin-film optical interference in metallic pigment flakes
- Primary manufacturers
- SICPA and others
- Reproducibility
- Cannot be replicated by scanning or standard printing
Common questions
What exactly is optically variable ink, and why do currency makers use it?+
OVI is a special ink that shifts color when you tilt it, such as green to blue on Indian ₹500 and ₹2000 notes. Printers use it because it is a public-facing security feature that ordinary people can verify by eye, making counterfeit notes easier to spot.
How does OVI actually work at the chemical level?+
OVI contains thin-film interference pigments made of metal and dielectric layers that create the color shift. Light bounces through these layers at different angles, producing different colors depending on how you view the note, and this optical behavior is nearly impossible to copy with a scanner or standard printing.
Which currencies use OVI besides Indian rupees?+
The US $100, Euro €50, and British Pound £20 all use OVI on their denomination numerals. This widespread adoption shows how effective OVI is as a global anti-counterfeiting standard.
Related terms
- Intaglio Printing
- A high-pressure printing process in which ink is forced into engraved recesses in a steel plate and transferred to paper, producing a...
- BOPP (Biaxially Oriented Polypropylene)
- The polymer film substrate for polymer-substrate banknotes (Australia, New Zealand, UK, Canada). Distinguished from cotton-linen paper notes by FTIR-ATR (CH3 methyl peaks...
- Security Thread
- A strip of metallised biaxially-oriented PET film embedded in the paper substrate, alternating between visible (windowed) and embedded segments. May carry magnetic...
- Banding
- Horizontal density variations across a laser or inkjet printed page, arising from developer roller irregularities, drum charging variation, or drive-train gear-skip; measurable...
- Cotton-Linen Substrate
- The traditional banknote paper substrate made from cotton fibre (and sometimes linen), containing no lignin, non-fluorescent under UV, textured under magnification; used...
- Daisy Wheel
- A circular print element with flexible plastic spokes each bearing a character, used in electronic daisy-wheel typewriters and printers from the late...
- Europol PEX (Project Ester)
- Europol's coordination framework for EUR counterfeit currency intelligence across EU member states, linked to the ECB's Counterfeit Monitoring System (CMS) and the...
- FICN
- Fake Indian Currency Notes. Counterfeiting and trafficking attracts UAPA 1967 Sections 15 to 17 (as a terrorist act when high-quality and large-scale)...
- FICN (Fake Indian Currency Notes)
- Counterfeit Indian banknotes, especially high-denomination ₹500 and ₹2000 notes. High-quality FICN (sometimes called 'super FICN') is coordinated under NIA investigation and intelligence...
- Fluorescent Security Ink
- An ink visible only under UV illumination at a specific wavelength (typically 365 nm), used to print denomination numerals, flag motifs, and...
- Golf Ball (IBM Selectric)
- Spherical typeball developed by IBM in 1961; rotates and tilts to bring the chosen character to the print position. Class link to...
- Goniospectrophotometry
- A spectrophotometric technique that measures reflectance spectra at multiple illumination and viewing angle combinations simultaneously, enabling quantitative characterisation of OVI colour-shift profiles...
Explained in these topics
- Counterfeit Currency: Security Features and Chemical AnalysisAn ink containing thin-film interference flakes (metal + dielectric layers, manufactured by SICPA and others) that produce a visible colour shift with viewing...
- Currency Security Features: Substrate, Threads, OVI, MicroprintingAn ink containing thin-film metallic flake pigments that shift colour depending on the viewing angle due to thin-film optical interference; cannot be replicate...
- Typescripts, Printed Matter, Currency and Mechanical ImpressionsColour-shifting ink that changes hue (green to blue on ₹500 and ₹2000) when the note is tilted. A primary public-check security feature.