Have you ever wondered why the colour of your passport is the colour it is? Approaching immigration control, the colour of your passport and of those around you is probably the last thing on your mind.
There is, however, more to it than you think.
According to Hrant Boghossian, the vice president of Arton Group, which runs the interactive passport database Passport Index, the shade of each national passport is derived from four main colours: red, blue, green or black.
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"Within each colour hue, we see vast variations," he said while speaking to Business Insider, adding, "There are in fact many passport colours."
Rules pertaining to the size and format of a passport are issued by the International Civil Aviation Organization (ICAO), however, governments around the world can also choose the colour and design of their national document.
For many countries, like Pakistan, the chosen passport colour may hold religious significance. Muslim countries, including Pakistan, Morocco and Saudi Arabia, for example have passports which are in different shades of green.
"Most Islamic states use green passports because of the importance of the colour in their religion," Boghossian said.
Green is believed to have been a favourite colour of Prophet Muhammad (pbuh), is a “symbol of nature and life”, and is seen on several of the national flags of Islamic countries such as Pakistan, Afghanistan and Iran.
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On the other hand, the passport books for countries within the European Union tend to be burgundy, while those from Caricom (Caribbean Community and Common Market) states use blue, which could be for geographical or political reasons.
"Some could argue that the burgundy red is due to a past communist history," Boghossian said, adding that "blue passports may be symbolic of the New World for countries in North America, South America and Oceania".
Having said that, "The passport of Turkey has changed to burgundy as it hopes to join the EU," he claimed.
Other countries, however, choose a certain colour to distinguish itself and reflect their unique identity, such as Switzerland, whose passport is bright red. Singapore’s passport bears a bright orange, reddish cover, while Canada’s temporary passport book for travellers in need of emergency travel documents has a white cover.
The US cover on the other hand has seen several changes in its colour, from red to green and now blue. The choice of colour for a country’s passport, though potentially influenced by culture and history, also comes down to practicality and availability.
“Passport production is a highly controlled process, and only few companies around the world are doing it," Boghossian explained.
The cardstock used for passport covers is "usually supplied by a third party" and "only comes in certain colour variations to meet the required standards," he added.
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'Hidden' artwork is also a feature of several passports, including those of Canada, Britain, US, China and Norway and is only visible under a special UV (ultraviolet) light.
Norway's new passport on the other hand is offered in either white, turquoise or red and its pages feature minimalist interpretations of the country’s most striking landscapes and scenery, including the otherwise elusive Northern Lights phenomenon which appears when placed under UV light.
A few Britons are believed to hold a unique Queen’s Messenger passport in Britain, which are said to be issued only to individuals relaying important messages or information to British consulates and embassies around the world.
This article originally appeared on Telegraph.