Numerous jewellery gifts from friends and family are held in the Queen’s jewellery box. As the Queen’s Sapphire Tiara was purchased to match a set of Victorian-era sapphire diamonds that she already owned, this tiara is also occasionally referred to as the “Victorian Sapphire Tiara.”
She got the set of sapphire jewelry—a necklace, earrings, and eventually a bracelet and ring—as a wedding gift from her father, King George VI, in 1947. (As a result, it is occasionally referred to as the “George VI Sapphire Tiara)

The Queen included this tiara as a single item later in her sapphire jewellery set. However, the origins of the tiara are centuries old.
History behind the Sapphire Tiara
It is a nineteenth-century sapphire necklace that had formerly belonged to Princess Louise of Saxe-Coburg and Gotha (born as Princess Louise of Belgium). It was one of the royal heirlooms Queen Elizabeth had acquired.
In picture below, Louise can be seen donning what is now known as the Queen’s tiara, but she usually wore it as a necklace or a dress accessory (in the image above, it is attached to the neck of her dress). You can see a little bit of pointiness in the current tiara, which is a big giveaway that it was originally a necklace that was turned into a tiara.

Louise was a controversial person with a long history of romances. After divorcing her husband, she became estranged from her family and fell into major financial difficulties.
Among several other things, she had to sell her jewellery to pay off her debt. The sapphire and diamond necklace is likely how it probably ended up on the general market. Where it was eventually purchased for the Queen. Later, it was transformed into a tiara.
If you look closely, it is evident that the piece was once a necklace because the diamonds that are now straight were once hinged drops on Louise’s necklace.
When did Queen wear it last time?
From the 1960s through the early 1990s, the Queen wore this item quite frequently before it was kept away in the royal locker for many years. However, the tiara unexpectedly reappeared during a state dinner for the Chinese president in 2015.

Nowadays, the Queen usually wears “white” jewels for evening wear. Therefore, it was interesting to see her bring out some colour for a change.