Where does “пьрстьнь” come from?

пьрстьнь (Old East Slavic) comes from Proto-Slavic pьrsty, from Proto-Slavic pьrstъ, from Proto-Balto-Slavic pírštan, from Proto-Indo-European pr̥-sth₂-o-m, from Proto-Indo-European per-, from Proto-Indo-European pr̥tós — passed , crossed.

Ancestry of “пьрстьнь”, step by step

StepLanguageWordMeaning
1Proto-Slavicpьrstyfinger ring; ring
2Proto-Slavicpьrstъfinger
3Proto-Balto-Slavicpírštanfinger
4Proto-Indo-Europeanpr̥-sth₂-o-mtip
5Proto-Indo-Europeanper-before, in front; first; to go through
6Proto-Indo-Europeanpr̥tóspassed , crossed
Every word from Proto-Indo-European pr̥tós →Every word from Proto-Indo-European per- →Every word from Proto-Indo-European pr̥-sth₂-o-m →