Um, I ** lived with ** a custom jeweler for 20 years, and worked in the office. So, yes, I do know what I’m talking about. In addition to the actual store work, I was part of the process where he made jewelry, ordered it from manufacturers etc, much more involved than waiting on customers and writing up sales, yes, even single handedly did an inventory and cleaning of every single ring, cufflink, bracelet, chain, charm, earring tie clip in the place.
Yes, the 10/14/18 refers to the ratio of gold to other metals, yes, the 10K is more durable for every day abuse (note,abuse not everyday wear). Yes, indeed class rings are astronomical amounts of $$ - last priced them about 8 years ago and about fell off the chair.
However, I disagree whole heartedly with your suggestion to folks to go with the 10 K for wedding rings etc. (although I agree 18 K is more for the special something that you don’t wear every day) The 14K will not, under normal use, be damaged significantly. If , of course, you work with tools and machinery, you should remove them first. but just wearing, typing, shopping, showering, nope, not a problem for quality 14 K.
and, this is MOST important - for those of you seeking gift advice for me: I prefer 14K yellow gold, no diamonds, but rubies, opals, sapphires and emeralds are welcome. 
Platinum’s nice, too…