The vanishing of moon at dawn and reappearance at night has obvious connotations of rebirth1. Position on mummies: necklace2. This amulet, mainly in faience, was produced from Dynasty 18 onwards2

Blue glaze, suspension loop broken L 1.5
Late Dynasty 18
© 2017 University College London
LDUCE-UC #1501

Gold H 1.4
W 1.0, T 0.1
Late Period
Brooklyn
Museum
#08.480.220

Red glaze with
soldered green
suspension loop
H 1.0 Late Dynasty 18
© 2017 University
College London
LDUCE-UC #1230

Blue glaze
H 1.7, W 1.6, T 0.8 
Undated
© The Trustees
of the British Museum
#EA7431

References

1Andrews C. Amulets of Ancient Egypt, 1994, p. 90 and Fig. 90a 2Petrie W M F. Amulets, 1914, p. 23 and Figs. 85k-l