The first recorded diamond engagement ring was commissioned in 1477 by Archduke Maximilian of Austria for Mary of Burgundy. This much is agreed upon. What the ring looked like is more complicated.
Contemporary descriptions suggest it was set with thin diamonds arranged in the shape of an "M" - for Mary. It was not, in other words, a solitaire. It was a monogrammed betrothal ring, made to order, personal, and distinctly political. This was a dynastic union, and the ring was one element of a larger diplomatic project.
The ring didn't establish a trend. Diamond engagement rings remained rare for the next four centuries, confined to royal and very wealthy circles for whom diamonds were accessible. Most people who got engaged gave and received something else entirely - or nothing.
What the Maximilian ring did was provide a precedent that later got cited when the diamond industry was looking for historical legitimacy. The industry could point to 1477 and say: see, this tradition is ancient. Maximilian started it. It's true that Maximilian existed and gave a ring. The claim that this began a tradition is stretching the evidence.
Traditions are often like this: a few genuine historical precedents, aggressively cited, with the gaps between them quietly glossed over. The De Beers campaign of 1947 did exactly that - borrowing five centuries of history to sell a norm that was, in practice, barely a decade old.
The engagement ring tradition as most people experience it today - diamonds, expected, required - is less than a century old. That doesn't make it less meaningful. But it's worth knowing the difference between a tradition that's been practised for five hundred years and one that was invented in your grandparents' lifetime.
