This enigmatic photo from the George Grantham Bain Collection has no date and is labeled simply "Queen Mother, Siam." The lady is shown in clothing that reflects Edwardian English styles, plus an incredible collection of pearls.

The queens of the Chakri dynasty were often half-sisters of their husbands; that is, they were the daughters of the previous king by his concubines. Although this type of royal close-kin marriage caused genetic problems for the ancient Egyptians and for the descendants of Victoria and Albert in Europe, the custom did not last long enough to have any evident effect in Siam/Thailand.

Most of the Chakri kings of Siam had three or four queens, plus dozens of concubines. The current king, Bhumibol Ayduladej, has just one queen - and she is a first cousin once removed, rather than a sister.