On February 24, 1981, Lady Diana Spencer and Prince Charles announced their engagement. It was the first time the public glimpsed Diana's now-iconic engagement ring.
Wearing a bright blue blazer and skirt, the then-20-year-old displayed a 12-carat oval sapphire surrounded by 14 solitaire diamonds and set in white gold.
While most royals engagement rings are custom made, Diana picked out this particular ring from a jeweller's catalogue. Meaning anyone could've purchased it.
She never specifically shared why she chose the colour or the style.
"There are a few different theories as to why Diana selected the ring: the colour matched her eyes, the Queen may have actually selected it, or as Diana was later quoted as saying, 'It was the biggest,'" The Crown's lead researcher Annie Sulzberger told Vogue UK. "Others claim that it simply reminded her of her mother's engagement ring."
Today, the ring is worn by Kate, the Duchess of Cambridge, as her own engagement ring.
Watch: Engagement rings through the decades. Post continues below.