A renowned diamond, once the possession of two of Europe’s most influential families, has resurfaced in the most unexpected of places.

The Florentine Diamond, a 137-carat gem once owned by the Habsburgs, has been located inside a Canadian bank vault, according to the New York Times.

For years, the stone’s disappearance fueled countless theories and sparked much intrigue.

Many speculated that the diamond had either been lost or stolen.

However, the Habsburg family has now revealed that the diamond has been securely stored away in a vault since the end of World War II.

The diamond’s storied history traces back to 1918, during the collapse of Charles I of Austria’s monarchy at the close of World War I.

At its height of power, the House of Habsburg was one of the leading and most influential rulers in Europe.

Charles I sent the diamond, as well as other centuries-old jewels, to Switzerland for protection as he went into exile.

The 137-carat Florentine Diamond was tracked down to a bank vault in Canada (photo of a glass replica of the gem)

Charles I sent the diamond to Switzerland for protection as he took exile (photo of Charles I with Queen Zita Von Bourbon-Parma)

After the monarch died in the Portuguese island of Madeira, his wife Zita of Bourbon-Parma and her children moved to Spain and later Belgium.

As Nazi rule spread across Europe, Zita and her eldest son, crown prince Otto von Habsburg, vehemently opposed Adolf Hitler’s rise.

But when the Nazis annexed Austria in 1938, Otto was declared an enemy of the state.

Zita was forced to flee again to the US two years later, the New York Times reported.

She carried the jewels, family members said, in a small cardboard suitcase.

With American assistance, the family reached Canada and settled in Quebec.

‘My grandmother felt very safe. She could breathe finally,’ said one of Charles I’s grandsons, Karl von Habsburg-Lothringen.

‘I assume that, at that stage, the little suitcase went into a bank safe, and that was it. And in that bank safe, it just stayed.’

The precious gem’s apparent disappearance had been the subject of rampant speculation for decades

Zita returned to Europe in 1953 and died in 1989 at the age of 96.

As she lived her life, the prestigious diamond remained in Canada – unbeknownst to the the world.

‘I think she wanted to make sure that it was not in her lifetime,’ Habsburg-Lothringen added.

‘I have the feeling she was very glad that some important objects of the family are something that she had saved.’

He said his grandmother understood the significance of the diamond.

‘That was historically very important for her,’ von Habsburg-Lothringen said.

‘Because she was somebody who was thinking very much in historic terms.’

The diamond’s authenticity was verified by Christoph Köchert, whose firm once acted as Austria’s imperial court jewelers.

Zita (right) and her eldest son, crown prince Otto von Habsburg (center), vehemently opposed Adolf Hitler’s rise

Köchert noted to the New York Times that the diamond’s cut pattern corresponded ‘almost exactly to representations in historical sources’ and that the stone’s authenticity was also confirmed using an electronic tester.

Before being property of the Habsburg family, the Florentine diamond had already belonged to one of Europe’s most powerful families.

The diamond was originally property of the Medici family in Florence, but entered the Habsburg dynasty in the 18th century through the marriage of Francis Stephen and Archduchess Maria Theresa of Austria.

The Habsburg family wants to display the diamond in Canada, as a gesture of gratitude toward the country that sheltered the empress and her children.

‘It should be on exhibition in Canada sometimes, so that people can actually see those pieces,’ Habsburg-Lothringen said.

However, the diamond could soon be on the move again.

Austria has committed to an ‘immediate review’ as to whether the diamond belongs to the country, per the New York Times.

‘If it turns out that the Florentine Diamond is the property of the Republic of Austria, I will initiate the process of returning the jewel,’ Austrian vice chancellor Andreas Babler said.