The story
From being a finger ring made of wrought iron, traditionally explained as being extracted from the debris cleared from the collapse of the Quebec Bridge.
Etymology from Wiktionary, CC BY-SA 4.0.
iron ring
Today it means: 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. Full definition →