iron ring

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.

iron ring (plural iron rings)

1. (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.
2. Used other than figuratively or idiomatically: see iron,‎ ring.

Borrowed from English iron ring.

iron ring m (plural iron rings)

1. (Canada, engineering) iron ring; Synonym of anneau de fer martelé

   Synonyms: anneau de fer martelé, anneau de fer

• anneau de fer martelé on the French Wikipedia.Wikipedia ^fr