Very rare "Palace stamps" from Siam/Thailand

These private stamps show photographic representations (portraits) of the royal family and were intended primarily for use by members of the ruling family within the palace area. Usually, one stamp was used for mailing within the palace area, and two stamps were used for mailing outside of it. There are only a few of these stamps in private hands. 

The illustrated pieces show the regency of King Chulalongkorn Rama V, plus a local stamp “Dusit Thani” (regency of King Vajiravudh Rama VI).