Noun
(Canada, engineering) The symbol of a Canadian engineer. A faceted stainless steel or iron ring worn on the little finger of the dominant hand, signifying a trained Canadian engineer, awarded in Canada after an accompanying oath of professional conduct, in a private ceremony with dramatic rites.
Used other than figuratively or idiomatically: see iron, ring.
Source: en.wiktionary.orgOn the carpet lay a pattern of markers, pebbles, an iron ring - junk. A random pattern. A crumpled sheet of paper blew towards Paradine. He picked it up automatically. Lewis Padgett
An iron ring made of wood. Hungarian Proverb