Editing Engagement ring (section)

===20th century===
In the United States, the popularity of diamond engagement rings declined after World War I, even more so than after the onset of the [[Great Depression]].<ref name="Russell2010">{{cite book|last=Russell|first=Rebecca Ross|title=Gender and Jewelry: A Feminist Analysis|url=https://books.google.com/books?id=Wx11yQK3J3QC&pg=PA50|access-date=10 November 2013|date=5 June 2010|publisher=Rebecca Ross Russell|isbn=978-1-4528-8253-6|page=50}}</ref>  

In 1938, the diamond [[cartel]] [[De Beers]] began a marketing campaign that would have a major impact on engagement rings. During the Great Depression of the 1930s, the price of diamonds collapsed.<ref>{{Cite news|url=https://www.bbc.co.uk/news/magazine-27371208|title=De Beers myth: Do people spend a month's salary on a diamond engagement ring?|last=Magazine|first=Laurence Cawley BBC News|work=BBC News|date=16 May 2014|access-date=2016-03-06}}</ref> At the same time, market research indicated that engagement rings were going out of style with the younger generation. Before World War II, only 10% of American engagement rings contained a diamond.<ref name=":0" /> While the first phase of the marketing campaign consisted of market research, the advertising phase began in 1939. One of the first elements of this campaign was to educate the public about the 4 Cs (cut, carats, color, and clarity). In 1947 the slogan "a diamond is forever" was introduced.<ref>{{Cite news|url=https://www.nytimes.com/2013/05/05/fashion/weddings/how-americans-learned-to-love-diamonds.html|title=How Americans Learned to Love Diamonds|last=Sullivan|first=J. Courtney|date=2013-05-03|newspaper=The New York Times|issn=0362-4331|access-date=2016-03-06}}</ref> Ultimately, the De Beers campaign sought to persuade the consumer that an engagement ring is indispensable, and that a diamond is the only acceptable stone for an engagement ring.<ref>{{cite book |last1=Otnes |first1=Cele C. |last2=Pleck |first2=Elizabeth |title=Cinderella Dreams: The Allure of the Lavish Wedding |date=2003 |publisher=University of California Press |isbn=9780520236615 |page=64 |url=https://books.google.com/books?id=OYBB_DGQN7kC&pg=PA64 |language=en |quote=Ayer promoted diamonds as indispensable luxury items that all “proper” engaged women should acquire.}}</ref> The sales of diamonds in the United States rose from $23 million to $2.1 billion between 1939 and 1979.<ref name=":1">{{Cite book|last=Shotton|first=Richard|url=https://books.google.com/books?id=Uc1MDwAAQBAJ&pg=PT149|title=The Choice Factory: 25 behavioural biases that influence what we buy|date=2018-02-12|publisher=Harriman House Limited|isbn=978-0-85719-610-1|language=en}}</ref>

Law professor Margaret F. Brining links the surge in engagement ring sales in the USA after 1945 to the abolishment of the "breach of promise", that had entitled a woman whose fiancé had broken off their engagement to sue him for damages.<ref>{{Cite web|last=Brining|first=Margaret F.|title=Rings and promises|url=http://homes.chass.utoronto.ca/~siow/332/rings.pdf|website=Originally printed in 6 Journal of Law, Economics, and Organization 203 (1990)}}</ref> This rule of law was especially important for many women who had been sexually intimate with the fiancé, but were socially expected to be virgins in a new marriage, therefore lost "market value". After the gradual abolishment of that law action in all states the expensive engagement ring rose to popularity as a new financial security in case of a break-up, since it was custom for the women to keep the ring (partly only under the condition that the break-up was not seen as her fault).