In his discussion of glass flasks of this general form Stefano Carboni notes that the tapering examples ("spear form") are likely to be later, and that those, as here, with parallel sides, which also show a greater variety in the colouring and decoration of the marvering, can be dated earlier (Stefano Carboni, Glass of the Sultans, New York, 2001, p.139). This idea is further developed with more examples in his discussion of vessels in the al-Sabah Collection, Kuwait (Stefano Carboni, Glass of Islamic Lands, London, 2001, pp.292, 296-9 and 304-5). All the examples have a dark translucent glass body, even if at times the colour is so dark that very little light gets through. The present bottle is remarkable in having a red opaque glass body, a colour that is normally only used for decoration. The red colour contains small streaks of dark within the glass, a feature that is found on the red used in details such as the bird's wings in lot 29, and also in a brilliantly coloured small bottle sold in these Rooms 23 October 2007, lot 80. The combination of these lighter brighter tones makes for a very striking alternative to the normally encountered examples of this form.