Diamonds, the Rare Treasures from the Depths

Once formed over 150 kilometers deep within the Earth’s mantle, diamonds now glitter on many a ring finger. A recent study sheds light on how these precious gems made their way to the surface. Through geological clues and model simulations, researchers revealed how the breakup of tectonic plates led to volcanic eruptions that brought these „treasure-rich“ materials within our reach.

Kimberlites are volatile-rich, occasionally diamond-bearing magmas that have erupted explosively at Earth’s surface in the geologic past1,2,3. These enigmatic magmas, originating from depths exceeding 150 km in Earth’s mantle1, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity4. Whether their mobilization is driven by mantle plumes5 or by mechanical weakening of cratonic lithosphere4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted about 30 million years (Myr) after continental breakup, suggesting an association with rifting processes. Our dynamical and analytical models show that physically steep lithosphere–asthenosphere boundaries (LABs) formed during rifting generate convective instabilities in the asthenosphere that slowly migrate many hundreds to thousands of kilometres inboard of rift zones. These instabilities endure many tens of millions of years after continental breakup and destabilize the basal tens of kilometres of the cratonic lithosphere, or keel. Displaced keel is replaced by a hot, upwelling mixture of asthenosphere and recycled volatile-rich keel in the return flow, causing decompressional partial melting. Our calculations show that this process can generate small-volume, low-degree, volatile-rich melts, closely matching the characteristics expected of kimberlites1,2,3. Together, these results provide a quantitative and mechanistic link between kimberlite episodicity and supercontinent cycles through progressive disruption of cratonic keels.

Diamonds are made of ordinary carbon, but what sets them apart from materials like coal is their purity and consistency. Naturally, their highly compact crystal structure can only form under immense pressure and heat in the Earth’s mantle, conditions found at depths over 150 kilometers. Over millions of years, diamonds were „baked“ in this extreme environment. The process of how they reached the Earth’s surface was roughly understood: diamond-bearing rocks melted due to geological processes, rose through fissures, and eventually surfaced during volcanic eruptions. The remains of these cooled volcanoes formed the deposits where raw diamonds are found today, typically embedded in a material known as kimberlite, named after the South African diamond-rich location, Kimberley. However, previous models couldn’t fully explain the origin of kimberlite melts deep within the Earth. It was evident that these processes were somehow linked to the restructuring of the Earth’s tectonic plates.

Unraveling the Mobilization Process

To investigate the geological processes leading to mobilization and kimberlite eruptions, the team led by Thomas Gernon from the University of Southampton delved into the matter. „The pattern of diamond eruptions is cyclic and follows the rhythm of supercontinents forming and breaking apart over hundreds of millions of years. However, until now, we didn’t know the process that suddenly brings diamonds to the Earth’s surface after resting 150 kilometers deep for millions or billions of years,“ says Gernon.

To gather new insights, the researchers analyzed the global correlation between the occurrence of kimberlites and the history of tectonic plate movements on Earth. They combined radiometric dating results with tectonic reconstructions, revealing that kimberlites formed over the past billion years typically erupted about 30 million years after the breakup of continental plates in the corresponding regions. This suggested an association with specific processes occurring at rift zones.

Natur Diamanten,natürliche Diamanten

Hot Processes at Plate Boundaries

To shed light on the exact mechanisms, the team developed geological model simulations that provided a plausible picture of the processes. According to their explanation, a continental plate thins considerably over many millions of years before it breaks apart. This process, known as „rifting,“ causes the Earth’s surface to sink, eventually forming a rift valley. This is currently happening in East Africa, where the Rift Valley is forming. The model suggests that something similar occurs deep within the Earth: pieces of the underside of the plate sink into the mantle while hotter rock flows in from below to fill the void—similar to seawater on the surface. This incoming magma destabilizes the surrounding rock containing diamonds, turning the previously ductile material into a liquid that then rises upward. Eventually, through volcanic eruptions, it reaches the surface and solidifies into diamond-rich kimberlite.

Furthermore, the researchers can explain why volcanic eruptions with diamond-rich kimberlite can occur relatively far from the continental edges. These eruptions are also ultimately caused by plate breakup. Dynamic processes that extend far and wide occur during this process. „These flows along the underside of tectonic plates remove a considerable amount of rock, dozens of kilometers thick. This chain reaction ultimately reaches regions of the continents that are far from rift zones,“ explains co-author Sascha Brune from the German Research Centre for Geosciences (GFZ) in Potsdam.

Princess Margrethe of Denmark |Royal Wedding Prince Rene of Bourbon-Parma | Fleur de Lys Diamond Tiara

On June 9th, 1921, an extraordinary couple exchanged vows in a church in Copenhagen, creating a wedding that defied convention and captured the attention of the world. This was no ordinary union, and the circumstances surrounding it were far from ordinary. The bride, Her Royal Highness Princess Margrethe of Denmark, was the daughter of Prince Waldemar of Denmark, himself the youngest son of King Christian IX of Denmark, and Princess Marie of Orléans. The groom, His Royal Highness Prince René of Bourbon-Parma, hailed from a Catholic family, and their wedding took place in the Catholic Sacred Heart of Jesus church, despite the Protestant background of the Danish royal family.

Princess Margrethe’s upbringing was unique, as she was raised in the Catholic faith despite being a member of the Protestant Danish Royal Family. This was due to her mother’s French royal lineage. When Prince Waldemar and Princess Marie married in 1885, it was decided that their sons would be raised as Protestants, while their daughters would be raised as Catholics. Princess Margrethe happened to be the only daughter born from this Protestant-Catholic union.

Fleur de lys in diamonds - Princess Margrethe of Denmark - Princess Renee of Bourbon-Parma Princess Margrethe of Denmark |Royal Wedding Prince Rene of Bourbon-Parma | Fleur de Lys Diamond Tiara Bryllupsgaverne. Mariage princier S. A. R. LE pRINCE RENÉ DE BOURBON- PARME VIENT D'ÉPOUSER S. A. R. LA PRINCESSE MARGUERITE DE DANEMARK  Prinsesse Margrethes Bryllup.

Born in September 1895, Princess Margrethe received the names Margrethe Françoise Louise Marie. Her baptism took place in her parents‘ home two days after her birth, followed by a grander christening ceremony witnessed by family members and public representatives, befitting her status as the granddaughter of the King of Denmark.

Tragedy struck at a young age when Princess Margrethe’s mother passed away in 1909, leaving her motherless at the age of 10. Prince René’s background was equally noteworthy, with his father being the Duke of Parma and his mother born an Infanta of Portugal. He came from a large family, with half-siblings and siblings, including the famous last Empress of Austria, Zita. His brother Felix married the Grand Duchess of Luxembourg, and one of his half-sister Marie-Louise , married Prince Ferdinand I of Bulgaria.

The announcement of the royal engagement on March 11th came as a surprise to many, including those close to Prince Valdemar’s family. However, there were indications that some preparations had been made prior to the announcement. Prince René, accompanied by his brothers, had arrived the day before to meet with Princess Margrethe’s family. The engagement was celebrated at a birthday reception and luncheon for the Danish Crown Prince, where the rest of the family had the opportunity to meet the groom-to-be. Various private dinners were hosted by Prince Waldemar and the Queen Dowager, providing further opportunities for the families to bond and celebrate the upcoming union.

Pre-wedding events continued in the days leading up to the wedding, following the tradition of Royal weddings of that era. Guests arrived, and festivities commenced, including a grand dinner and ball hosted by Prince Waldemar at Bernsdorff Palace. The Royal guests, along with Princess Margrethe’s friends, enjoyed the enchanting evening adorned in elegant attire, captured in a photograph that immortalized the moment.

The photograph revealed a display of tiaras and jewelry, worn by the distinguished guests. Details regarding the specific events and their tiara usage were scarce due to the private nature of these occasions.

The wedding day arrived on June 9th, 1921, with preparations taking place at Bernsdorff Palace. The exterior was decorated with greenery, Danish flags, and the initials of the couple, creating a picturesque scene. Inside the church of the Sacred Heart of Jesus, invited guests, including representatives from official authorities, courtiers, and members of the Danish Catholic community, filled the pews. The church itself was adorned with a tasteful and impactful decoration scheme, featuring palms, ivy, rhododendrons, and hydrangeas.

Floral crosses representing both the Danish and French flags adorned the altar.

The Royal guests arrived at the church and were received by the Marshal of the Court, Chamberlain W. Rothe, and other dignitaries. The procession, led by the King and Queen, Prince René and his mother the Duchess of Parma, the Queen Dowager, and other Royal family members, made their way down the aisle to their designated seats. The anticipation grew as the moment approached for the bride and her father to make their entrance. Princess Margrethe, radiating joy, walked beside her father, her magnificent lace train held in place by a wreath of myrtle and orange flowers, accentuated by a delicate diamond tiara, a gift from the groom.

Following the church ceremony, the Royal family returned to Amalienborg, where a luncheon was hosted in their honor. The guests, who had received invitations, extended their congratulations to the newly weds and enjoyed a sumptuous meal accompanied by music and Danish and French melodies. The grandeur of the occasion was enhanced by the beautifully decorated tables adorned with pink roses and the sparkling crystal used for the dining experience.

Outside the palace, crowds of people had gathered, eagerly awaiting a glimpse of the newly weds. Princess Margrethe and Prince René made a balcony appearance, waving to the enthusiastic crowd, before returning inside to continue the luncheon. The celebrations concluded with the departure of the couple, bidding farewell to their family members, and embarking on their journey together. As they left, well-wishers showered them with rice and flowers, adding to the joyful atmosphere.

The wedding of Princess Margrethe and Prince René was a remarkable event that captured the imagination of the public. It defied expectations and highlighted the union of two individuals from different backgrounds and faiths. The day was filled with love, joy, and a sense of unity, as the Royal families and their guests came together to celebrate this extraordinary marriage.

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Ruby Diamond Wreath Spray Brooch Tiara | Empress Josephine Imperial France

the first posting of this jewels is from the year 2007…the ruby and diamond brooch, wearable as wreath diadem….

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