A sensational 37-carat emerald brooch commissioned by Prince Aga Khan for his wife, Nina Dyer, in 1960, and then sold at Christie's Geneva in 1969 for $75,000, is returning to the venerable auction house on November 12 carrying a pre-sale estimate of $6 million to $8 million.

The unusually transparent and evenly colored emerald is bordered by 20 marquise-shaped diamonds boasting a total weight of 12.04 carats. Christies wrote that the brooch/pendant designed by Cartier Paris epitomized the elegance and sophistication of its era.

Accounting solely for inflation, an item that sold for $75,000 in 1969 would be worth $642,000 today. If the Aga Khan fetches somewhere in the mid-range of its pre-sale estimate, say $7 million, the true value of the piece would have accrued by a magnitude of more than 10.

The Aga Khan assumed the role of the spiritual leader of the Shia Imami Ismailia Muslims in 1957, at age 20, after succeeding his grandfather. It was that same year that he married Dyer, a strikingly beautiful socialite and model, who was six years his senior.

Dyer's first marriage was to billionaire Baron Hans Heinrich von Thyssen, heir to the Thyssen steel and armaments empire. Their three-year marriage ended in 1956.

According to Christie's, like many of the beautiful jewels commissioned by the Aga Khan for Dyer, she wore this exceptional piece at numerous prominent events.

In 1969, the Aga Khan emerald brooch was purchased by Van Cleef & Arpels at Christie's inaugural Magnificent Jewels sale at Le Richemond Hotel in Geneva. Later, it was sold to luxury jeweler Harry Winston.

“The emerald brooch is not just a piece of jewelry. It carries with it the stories and charm of a bygone era,” commented Max Fawcett, Christie’s Head of Jewelry Europe. “We are thrilled to present it once again, not only because of its history, but also due to the increased interest in colored stones the market has witnessed in recent years."

He noted that the 37-carat Colombian emerald shows no indications of clarity modification and is accompanied by an SSEF report stating the exceptional quality and rarity of the stone.

"We might see an emerald of this quality come up for sale once every five or six years," said François Curiel, Christie’s chairman EMEA. "It’s an exciting opportunity for jewelry collectors to acquire one of the rarest treasures on Earth."

The first time Curiel laid eyes on the Aga Khan emerald brooch, he was a 21 year old and fresh out of gemological school. It was 55 years ago when he accompanied his father to both the dealer preview and the inaugural Magnificent Jewels evening auction.

The Aga Khan and Dyer divorced in 1962 and, suffering from depression, she died from an overdose of sleeping pills in 1965 at age 35.

Credit: Photo courtesy of Christie's.