Princess Margaret was the only sister of the Queen and she sadly died in February 2002. She married Antony Armstrong-Jones at a wedding which took place at Westminster Abbey.
It continued into a full length skirt and had a faint floral pattern across it.
As is royal tradition, she dressed up the look with a headpiece and opted for the Poltimore tiara.
Princess Margaret and her husband went on to have two children.
The couple had met just one year before they got engaged.
Antony proposed in October 1959 and the Queen’s sister was given a unique ring.
Far from the traditional diamond, Princess Margaret sported a ring with a central ruby.
Designed by Antony himself, the ruby was surrounded by diamonds to create the shape of a rosebud.
This was done in a nod to Princess Margaret’s middle name, Rose.
The design of the ring was unique both at the time and with styles today, experts at The Vintage Ring Company explained.
They said: “What makes this vintage style of halo different to contemporary designs is the size of the diamonds.
“Similar in proportion to flower petals, these old-cut stones are much larger than those commonly chosen for halos by jewellers today.
“The colour of the ruby in Margaret’s engagement ring is a sumptuous pink-red, a subtle but incredibly romantic nod to her middle name, Rose.
“This hue is further enhanced by the yellow gold of the ring’s settings and band; a timeless colour marriage that oozes vintage charm.
“Though gorgeous, a ruby with a lighter tone carries a considerably smaller price tag than one in an intense shade of red.”
If sold today, the experts gave it a valuation of around £8,000.
They added: “Today, I’d value a ring like this one just below the £8,000 mark, but it’s tricky to be certain without an idea of the quality of that central stone and the exact size of the halo diamonds.”