The whole point of an amulet cartouche, an elongated shen, was to include a king’s name. Most are blank to assimilate the wearer to the king.
Materials are mainly lapis lazuli and stones. Rare examples are topped by double plumes. Position on mummy: upper torso close to the shen sign1. Period: Dynasty 26 onwards2

Lapis lazuli H 2.2, W 1.1
Late Period
© 2017 University College
London LDUCE-UC #52030

Brown hematite with
plumes H 2.8 Undated
© Musée du Louvre/
Antiquités égyptiennes
#E 3155

Basalt H 1.7, W 1.1
Late Period
© 2017 University
College London
LDUCE-UC #52031

References

1Andrews C. Amulets of Ancient Egypt, 1994, p. 77 and Figs. 77b,c
2Petrie W M F. Amulets, 1914, p. 21 and Figs. 78a,b