The Star of Sierra Leone: Largest Alluvial Diamond

Leone is one of the world’s largest documented diamond finds and one of the largest precious stones ever discovered. It was unearthed on 14th February 1972 by a group of diamond miners working on the Diminco alluvial mines located in the Koidu region of Sierra Leone. Diminco is an abbreviation for Diamond Mining Company—a state-sponsored mining and exploration company in Sierra Leone.

The Star of Sierra Leone has been ranked the fourth-largest gem-quality diamond ever discovered. However, it is still the world’s largest diamond in alluvial mines. At its discovery, the Star of Sierra Leone weighed 969.8 carats. The stone would change the country’s fortunes, and a significant media spotlight surrounded its discovery. Given its fame, the Sierra Leone government took the initiative of marketing the diamond.

On 3rd October 1972, the then Sierra Leone president, Siaka Stevens, announced a deal to sell the Star of Sierra Leone. The deal was secured with the New York City jeweler Harry Winston for just below $2.5 million.

But even before this, Sierra Leone was familiar with historical diamond finds. Two years before the discovery of the Star of Sierra Leone, the Sefadu diamond held the record as the country’s largest diamond find, weighing 620 carats.

Diamonds obtained in Sierra Leone have an international reputation for being some of the highest-quality gems. Such diamonds are lauded especially for their purity and clarity, mostly with minimal inclusions. This makes their processing easy and their sale lucrative. Sierra Leone diamonds are so clear, colorless, and transparent that they are often called “glasses.” However, it is important to note that the diamonds cut from the Star of Sierra Leone are yet to be graded for clarity and color. All the same, gem experts believe that they are likely D-color diamonds and largely flawless.

The Star of Sierra Leone is a colorless, pellucid, and lustrous crystal. As you may know, these features are associated with superior-quality diamonds.

Another unique attribute of the diamond is its perfect chemical purity, resulting from the absence of the common impurities that commonly accompany precious stones. Examples of such impurities include boron, nitrogen, and hydrogen. Besides, the stone is also structurally perfect. Structural perfection is attributed to the crystal's lack of visually-perceptible plastic distortions. A diamond's chemical and structural characteristics impact its quality, brilliance, and clarity. Since the Star of Sierra Leone has no chemical or structural flaws, it scores remarkably high in the diamond color range and clarity scale.

Due to these unique attributes, the Star of Sierra Leone ranks as a Type IIa diamond—less than 1% of the world’s diamonds fall under this category. Thus, besides its exceptional quality, the Star of Sierra Leone also belongs to a league of the few.

Harry Winston purchased the Star of Sierra Leone the same year the diamond was discovered. After acquiring the diamond, Lazare Kaplan was entrusted with the cutting process, though it could not commence immediately.

During this time, Lazare Kaplan was among the few world-renowned diamond cutters and cleavers, having demonstrated a long history of excellence in the trade. Mr. Kaplan descended from three generations of expert diamond cutters. The earlier members of his generation had learned and perfected the art of diamond cutting and cleaving in Antwerp, Belgium. One of their most notable works was the successful cutting of Jonker in 1936.

Lazare Kaplan’s experience in the trade saw him pioneer the establishment of Puerto Rico’s diamond-cutting industry. At the time, he was about to bring this experience in cutting the world’s largest and most famous diamond.

Kaplan studied the Star of Sierra Leone carefully. As usual, he focused more on bringing out maximum sparkle and brilliance in the diamond. Lazare Kaplan spent around one year visualizing how the stone would look after cutting. When the day for cutting finally arrived, the event was broadcast live on television. Therefore, the diamond is not only a treasured gem in Sierra Leone but is also quite revered in America. When the cutting process ended, the Sierra Leone government issued a unique commemoration stamp, marking this event. The stamp had a special feature: a diamond-like shape complete with a crown, a table, and a pavilion.

Initially, the Star of Sierra Leone was cut into an emerald-shaped stone weighing 143.2 carats. However, the diamond's numerous significant inclusions marred its clarity and overall rating. Hence, it was only logical to cleave it further. Subsequent cleaving eventually reduced the stone into seventeen separate pieces. Out of these, thirteen were considered flawless. The largest stone out of the flawless pieces was a pear-shaped diamond that weighed 53.96 carats. Harry Winston set six cuts from the original rough diamond into the "Star of Sierra Leone" brooch.

The Star of Sierra Leone will go down in history as the world’s most historic diamond finds, one whose cutting and processing generated massive media publicity. The immense economic and sentimental value that the Government of Sierra Leone attached to the diamond is one reason behind its fame. Cullinan, weighing 3,106 carats and discovered in South Africa in 1905, may still be the world’s largest diamond find. Be that as it may, the Star of Sierra Leone ranks higher in purity and superior quality, like most Sierra Leone diamonds.