Here’s an interesting take on the engagement ring traditions, taken from Emily Post’s Pocket Book of Etiquette, 1970.  Check out the image below, if you want to read it “in the flesh”.

THE ENGAGEMENT RING

It is doubtful that the man who produced a ring from his pocket upon the instant that she said “Yes” often existed outside romantic novels.  In real life, the fiance first goes alone to the jeweler, explains how much he can afford and has a selection of rings set aside.  He then brings his fiancee into the store and lets her choose from among them the ones she likes best, perhaps one of platinum and diamond design or a lovely ring in her own birthstone.  Any good jeweler has a correct list of birthstones and can make suggestions as to the cut and color.

One popular trend today is that of using semiprecious stones, beside which the tiny diamond has lost its appeal:  an aquamarine, amethyst or a topaz or transparent tourmaline is perfect for an engagement ring.

The engagement ring is worn for the first time in public on the day of the announcement.  But the engagement ring is not essential to the validity of the betrothal.  The wedding ring is a requirement of the marriage service.  The engagement ring on the other hand is simply evidence that he has proposed marriage and that she has answered “Yes!”  Countless wives have never had an engagement ring at all, many receive these rings long after marriage.  Some brides prefer to forego an engagement ring and put the money it would have cost toward furnishing their future home.

…

IF SHE GIVES HIM AN ENGAGEMENT PRESENT

The girl may give the man an engagement present or not as she chooses: a set of studs and a matching pair of cufflinks, or a watch.  But she does not give him an engagement ring.

Marilla, Anne’s adoptive mother, has an amethyst brooch that she wears to church every Sunday.  When Anne (age 11) first sees it, she proclaims:

“Oh, Marilla, it’s a perfectly elegant brooch.  I don’t know how you can pay attention to the sermon or the prayers when you have it on.  I couldn’t, I know.  I think amethysts are just sweet.  They are what I used to think diamonds were like.  Long ago, before I had ever seen a diamond, I read about them and I tried to imagine what they would be like.  I thought they would be lovely glimmering purple stones.  When I saw a real diamond in a lady’s ring one day I was so disappointed I cried.”    L.M. Montgomery, Anne of Green Gables, Chapter XIII.

Later, when Anne and Gilbert Blythe were engaged, “Anne’s engagement ring was a circlet of pearls.  She had refused to wear a diamond.”  She told Gilbert: “‘I’ve never really liked diamonds since I found out they weren’t the lovely purple I had dreamed.  They will always suggest my old disappointment.’”    L.M. Montgomery, Anne’s House of Dreams, Chapter III.