The tjet amulet is an amulet of protection closely associated with Aset. Known as the "knot of Aset" and the "girdle of Aset", the specifications for the tjet are given in chapter 156 of The Book of Going Forth By Day. The tjet amulet resembles an ankh with its arms pointed downward. According to The Book of Going Forth By Day, the tjet amulet should be carved from red jasper stone.

The tjet amulet has associated words of power that invoke and recharge its protective powers, as given in chapter 156 of The Book of Going Forth By Day:

You have your blood, O Aset;
you have your power, O Aset;
you have your magic, O Aset.
The amulet is a protection for the Great One
which will drive away whoever
would commit a crime against her (or him).