Parallel for this shabti published in G. Janes nr. 102 a-f, as well as a further example in the Louvre, where they in had acquired a lot of seven small plaques in 1999 also from his tomb, filled with exceptional quality items. This Horemheb was a renep priest.
This shabti is from Egyptian blue (faience). From the Old Kingdom onwards amulets were sometimes made of Egyptian blue, an artificially produced frit consisting of calcium-copper-silicate.Superficially it can be mistaken for glazed composition which has lost its
shiny appearance, but, unlike composition, where the glaze is only on the surface, the colour is uniform throughout.
Reference: Carol Andrews, Amulets of ancient Egypt, pg. 102. Although not published, I have been told by an IADA dealer that he has also sold a shabti of this Horemheb from glassy faience, another rare material for shabtis but typical for the period, early 26th Dynasty probably (see the Hor-Khebi, Schneider 188.8.131.52).
This example is from a very high quality, much better than most of the shabtis still circulating the antiquities market.