Diamonds were first marketed with a vengeance back in the late 1920s in America. Film stars and celebrities were plied with diamond jewellery to increase the pubic awareness and desire for it.
It is believed that the advertising agency hired by de Beers at this time was the source of the “rule-of-thumb” that a loving boyfriend should purchase a diamond ring worth at least a month of his salary for his fiancée-to-be.
This has certainly been perpetuated and reinforced because I have had friends explain to me that it is actually 2 or even 3 months salary spent on the ring.
It was a fantastic piece of marketing because it ensured that the minimum spend on each diamond bought was likely to be a month of the average gentleman’s salary, because no loving boyfriend would not want to conform to the public (and his girlfriend’s) perception of how much should be spent if he was truly in love with
the woman.