Glossary

The science, study or collecting of coins, medals, paper money and related objects. In the scope of banking services, the numismatic service deals with the sale of legal, former or rare banknotes and coins to customers with collecting interests.

A price that is given to a numismatic object. It may deviate from the face value as a result of various factors: the degree of rarity, the state of the object’s preservation, the artistic relevance and the historical significance.

A collector or knowledgeable person in the field of numismatics.

Light from the side, falling at a shallow angle, and revealing the surface structure of an object through contrasts of light and shade. Oblique light is used especially to inspect embossing stamps, intaglio printing, latent images and mechanical erasures.

With a banknote, this is the main side that portrays the most representative motif, often the effigy of a ruling monarch or state symbol. With a coin, it is also the main side or face where a state symbol or portrait of the monarch and name of the country usually appear. The front side of a coin is commonly called ‘heads’ in coin tossing, while the other side is called ‘tails’.

An indirect printing process whereby ink is spread on a metal plate with etched images, then transferred to an intermediary surface such as a rubber blanket, and finally applied to the substrate by pressing that substrate against the intermediary surface. With wet offset, the printing plate must be moistened with water before it is inked, whereas dry offset printing does not use water. Offset is often used in long secure document print runs and is the most common printing method for tax stamps.

The optical property of a substrate that prevents transmission of light.

The reading and recognition of characters using an optical device.

Overt and semicovert security features with dynamic characteristics that change according to the viewing angle – eg. from one colour to another, or from one image to another.

A popular type of secure printing ink that contains microscopic pigments acting as interference filters, resulting in large colour shifts determined by the angle of lighting or viewing.

Process to check security features visible with simple smartphone cameras, such as diffractive motion effects based on the viewing angle.

Allows static controls using cameras at multiple wavelengths (visible and infrared light).

The process which transforms an initial design of a banknote or security document into an industrial product ready for printing.

A single-run multicolour printing method invented by Ivan Orlov in 1890 in Russia. Consists of creating separate ink layers on colour-separated plates and transferring the inks to a common plate and then to the receiving surface.

Security features such as holograms that are apparent to the human senses – especially those of sight and touch – without the need for additional readers and instruments. Such features are designed to enable all stakeholders, including the public, to identify if something is genuine or not.

Name of a widely used colour matching system in graphic design, whereby each colour is coded with a reference number.

The most widely used banknote substrate throughout history, usually made from cotton, with short fibres that give a banknote special characteristics of touch, sound and firmness. It can also include other fibres of different origins.

The phenomenon in an image which allows depth to be judged from the movement of near image elements relative to more distant ones. Traditional embossed holograms only display parallax from side to side, but the lack of vertical parallax is rarely noticed. Ortho-parallax is the term for when the movement of the elements is in a counterintuitive direction (ie. 90°) to the angle of view.

A security feature that requires an action such as scanning or photocopying to become visible. See also Active security feature.

Documents that can be used legally to effect payment in commercial banks in book money or currency. For example, cheques, bills of exchange, promissory notes.

A payment platform or network that moves money from payer to payee. Credit card rails are the credit card payment system.

Traditionally, PSPs have provided shops with online services for accepting electronic payments by a variety of payment methods including credit card, bank-based payments such as direct debit, bank transfer, and real-time bank transfer based on online banking. Typically, these are a software-as-a-service model and form a single payment gateway for clients (merchants) to multiple payment methods. For central bank digital currencies, PSPs are likely to facilitate the acceptance and use of CBDCs for payments.

Visibly similar to iridescence but with a slightly ‘milky’ appearance at certain viewing angles.

The fraudulent practice of sending emails or other messages purporting to be from reputable companies in order to induce individuals to reveal personal information, such as passwords and credit card numbers.

A type of fluorescence that continues for a period of time after the stimulus that produced the emission has stopped.

A light-induced reversible colour change which in its most familiar form involves an ultraviolet-induced transformation from colourless to coloured. Sunglasses that darken in the sunlight and revert to near colourless in subdued light constitute the most widely known application of photochromism. However, there are a diverse range of other applications and potential applications that include fuel markers, security inks and electronic nanotechnology.

Luminescence produced by exposure to ultraviolet light.

Holograms produced from materials that polymerise (combine to form a polymer) under the action of light energy and thus change their refractive index. Used to record volume reflection holograms (see Volume hologram).

A light-sensitive material used in processes such as photolithography and photoengraving to form a patterned coating on a surface. A substrate is coated with a light-sensitive organic material. A patterned mask is then applied to the surface to block light, so only unmasked areas are exposed. A solvent, called a developer, is then applied to the surface. In the case of a positive photoresist, the photo-sensitive material is degraded by light and the developer dissolves away exposed areas, leaving a coating where the mask was placed. In the case of a negative photoresist, the photo-sensitive material is strengthened (either polymerised or cross-linked) by light, and the developer dissolves away areas not exposed to light, leaving a coating in areas where the mask was not placed. This process is used to create surface grating images, which are the first stage in producing embossed holograms.

A device that utilises the unique, random, physical variations which occur naturally in a physical structure and which provide that structure with a ‘fingerprint’ that serves as a unique identifier. See also Fingerprinting – document.

A range of technologies whereby a material is released from a source and deposited on a substrate using a mechanical, electrochemical or thermodynamic process.

A process in which coin blank proofs are cleaned in acid to remove oil, directional rolling lines and dirt from their surface.

In digital imaging, a pixel (or picture element) is the smallest item of information in an image. Pixels are arranged in a 2D grid, represented by squares. Each pixel is a sample of an original image, with more samples typically providing more accurate representations of the original.

A coloured or reflective disc containing a security feature and embedded in paper during manufacture.

Plasma is superheated matter – so hot that the electrons are ripped away from the atoms, forming an ionised gas. It comprises over 99% of the visible universe. In the night sky, plasma glows in the form of stars. That branch of lightning that cracks the sky is plasma. So is the sun… and so are neon signs on city streets. Plasma is often called ‘the fourth state of matter’, along with solids, liquids and gas. Just as a liquid will boil, changing into a gas when energy is added, heating a gas will form a plasma – a soup of positively charged particles (ions) and negatively charged particles (electrons).

In physics, a plasmon is a quantum of plasma oscillation. Just as light consists of photons, the plasma oscillation consists of plasmons. The plasmon can be considered as a quasiparticle since it arises from the quantisation of plasma oscillations,

The generation, detection, and manipulation of coherent electron oscillations (known as surface plasmon polaritons), as they travel together with an electromagnetic wave along the interface between a metal (eg. silver, gold) and a dielectric material (eg. glass, air) at the nanometric scale. Inspired by photonics, plasmonics follows the trend of miniaturising optical devices, and can be applied as a security feature. The plasmons can be controlled through careful modelling and application of, among other things, the dielectric and metal layer thickness in a ‘sandwich’ structure. When the sandwich structure is applied as a device to a security document, it allows light that falls on the surface of the device to be controlled in terms of its wavelength (allowing control over the colour) and amplitude (giving rise to the intensity, or brightness of the colour generated).

A model made during the coin design process, approximately four times larger than the actual size of the final coin or medal.

A device allowing the use of payment cards at a physical (not virtual) point of sale. The payment information is captured either manually on paper vouchers or by electronic means.

The alignment of the electric and magnetic fields in a particular orientation in a lightwave. If all the waves in a beam of light move up and down or from side to side together, the beam is said to be plane-polarised. Some materials have the ability to filter out all lightwaves except those in a particular direction. Other materials are said to be optically active if they are able to change the angle of a plane-polarised beam of light. Liquid crystals often have this property and this enables them to be detected.

An optical device which transforms unpolarised light into polarised light. It is used to examine light reflected from ink or thin-film coating. It blocks light rays of a specific polarisation direction while letting light rays of other polarisation directions pass.

A thermoplastic polymer resin of the polyester family, used to make the most common container in the soft drink market today: the plastic bottle. Also used as the base material for most surface-applied holograms and security threads.

A substance or material consisting of very large molecules, or macromolecules, composed of many repeating subunits. Plastic and polyester are all polymers. Polymer banknotes were first introduced in Australia and are widely used around the world.

A laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA, which can then be studied in greater detail.

The act of converting a paper banknote design for use with polymer substrate.

The holding of banknotes/CBDCs as a store of value, for saving purposes or as a precaution for uncertainties.

Preparatory work required on original materials, such as films, files and plates to carry out the printing of a banknote or other security document.

In colour printing, print registration is the layering of printed patterns to form a multicolour image. Registration error refers to position misalignment in overlapped patterns, resulting in printed colours in the wrong areas, overprint or white space.

A plant for producing banknotes and other security documents. Printworks can be either state or central bank-owned or run by commercial companies.

The overprinting of two or more coloured inks to create a blended colour affect that is difficult to match on copiers. Prismatic colour blending is visually similar to split fountain printing, but differences become apparent when the images are magnified.