Iron Ring
Random trivia: the "iron version" picture is of my own ring, uploaded a few years back when I was messing around with my friend's new camera.  Pleasant surprise not only to see this on HN, but to see that the picture is still there after all this time :)As far as I know my year (2005) was one of the last years that U of T still offered an actual iron version, as opposed to stainless steel (most other schools no longer did at that time).  I'm not sure if it's still possible to get one today.  Another option was to get an old ring from retired engineers who were no longer practicing and returned their ring to be used by the next generation... something that I thought was pretty amazing and humbling.