An amulet of reflection conveys extrinsic reflection when worn.
Amulets comprise 1% of all randomly-generated items in the main dungeon, 1% in containers, and 4% in Gehennom. There is a 7.5% chance that a randomly-generated amulet will be an amulet of reflection. There is also a 50% chance that it is in the treasure zoo at the top of Sokoban.
This amulet auto-identifies when something reflects from it. Monsters will also don amulets of reflection. Therefore an amulet worn by a monster that isn't an amulet of life saving is an amulet of reflection.
If you don't want to wait for a monster to zap you, you can zap a suitable wand or spell at a wall and see if it hits you on the rebound. A wand of magic missile is ideal for this, since it does less damage than elemental wands, won't harm your equipment, and is of little use otherwise.
|"But it reflects from your medallion!"||Something reflected from the amulet|
Reflection is a very important property and the amulet of reflection is a very good source of it. It should be worn at all times until another source is found (e.g. SDSM).