The present diptych may be grouped among Koechlin's 'diptyques à colonettes', whose common feature is the use of vertical registers divided by slender columns. For the composition, compare a diptych leaf in the British Museum with two vertical registers illustrating the Annunciation and the Nativity (inv. no. 1856,0623.78). The 'colonette' group has sometimes been localised in Cologne; a possible German origin of the present diptych is suggested its the mannered, elongated figures.
O. M. Dalton, Catalogue of the Ivory Carvings of the Christian Era, cat. British Museum, London, 1909, no. 304; R. Koechlin, Les Ivoires gothiques français, Paris, 1924, vol. II, pp. 183-187; P. Williamson and G. Davies, Medieval Ivory Carvings: 1200-1550, cat. Victoria and Albert Museum, London, 2014, Part I, pp.300-301, no. 100
A Radiocarbon dating measurement report (ref. no. RCD-9080) prepared by J. Walker of RCD Lockinge, dated 30 May 2018, states that the ivory dates between AD 1315 and 1416 (95% confidence interval).