The taped-up collar was obvious when the All Black centre came off the bench in the Blues game against the Highlanders in Dunedin on Saturday night.
It was understood Williams, who is Muslim, covered the logo for religious reasons.
Muslims believe the charging of interest is prohibited by the Quran.
As a part of their collective agreement any player can lodge a conscientious objection to promoting finance, alcohol, tobacco, gambling companies and banks.
