Hrant Boghossian from the Arton Group, which runs the Passport Index, said travel documents are either red, black, blue or green.
He added: “Within each colour hue, we see vast variations. There are in fact many passport colours.”
There are “many possible scenarios” that lead countries to choose their own colour, according to Mr Boghossian.
The British passport falls into the ‘red’ category with its shining burgundy hue.
All EU member states have the same colour, with the exception of Croatia.
There are several theories as to why this colour was chosen, including a sign of unity between nations.
Mr Boghossian says it’s likely mired in communist ties.
He said: “Some could argue that the burgundy red is due to a past communist history.
“The passport of Turkey has changed to burgundy as it hopes to join the EU.”
The Andean Community of Bolivia, Colombia, Ecuador, and Peru also have burgundy passports.
Switzerland falls into the same colour category with its bright red travel document, to match its national flag.
Thought to have been the favourite colour of the Prophet Muhammad, green is often used for religious reasons.
Mr Boghossian said: ”Most Islamic states use green passports because of the importance of the colour in their religion.”
Morocco, Saudi Arabia, and Pakistan all fall into this category.
Economic Community of West African States – including Niger and Senegal – also have green passports.
The US passport was changed to blue in 1976 but has also been red and green
The Swiss passport is red to match the colour of its flag
Believed to represent the “new world”, the colour blue has been chosen by 15 Caribbean countries.
South American nations including Brazil, Argentina and Paraguay also use blue passports.
The US adopted a blue travel document in 1976, but has used the colours of red and green in its past.
Canada and Australia have also chosen shades of blue.
This colour is often used for practical reasons, with dark colours showing up less grime and general wear and tear.
Black passports are used by New Zealand because it is the country’s national hue.
The Republic of Botswana and Zambia