"A few decades ago, heritage scientists and art historians started to study the ancient surface colouring techniques of metal art pieces. Colouring of copper and silver has already been broadly studied but no works on gold have been reported yet. This knowledge can be very important for art and technology history, conservation‐restoration and surface sciences. This paper contributes to the investigation of the oldest recipe known so far to colour fire gildings. The chosen model samples, the mixture and the application of the recipe have been summarised by referring to the ancient writings known as the Arab and Syrian Alchemist Collection of M. Berthelot."