The Spoonmaker Diamond, one of the most celebrated gems in the Turkish Crown Jewels, has an uncertain and intriguing history. Since the early nineteenth century, it has remained in the possession of the Turkish government and is currently displayed at the Topkapi Palace Museum in Istanbul, where it continues to captivate visitors with its size, brilliance, and mystery.

Despite its fame, there is considerable discrepancy regarding the diamond’s true weight. Historical records cite it as weighing 86 carats, yet early nineteenth-century documents refer to it as the third-largest diamond in the world. This claim conflicts with known data, as several other famous diamonds—such as the Orlov (189.6 carats), Darya-i-Nur or Great Table (minimum 175 carats), Koh-i-Noor (estimated 186 carats), Florentine (137.27 carats), Nassak (90 carats), and Shah (88.6 carats)—would have surpassed it in size. This suggests a long-standing error in the historical record, possibly dating back more than two centuries.

The cut of the Spoonmaker Diamond has also been the subject of debate, with its shape directly influencing its calculated weight. When modelled as a double Dutch rose cut, where the crown and pavilion are mirror images, a diamond measuring 42 x 35 x 16 millimeters would weigh approximately 153.5 carats (natural diamond), or 258.9 carats in cubic zirconia equivalent. A CZ replica of the Spoonmaker, cut to precise dimensions, weighs 270 carats, a discrepancy of only 11 carats, easily accounted for by slight measurement variations.

Some gemmological sources, including Balfour, describe the stone as a “bizot cut.” However, no definitive explanation of this term exists in the literature. It may imply a design where the back of the diamond is flat and only the upper surface is faceted, a style that enhances brilliance when paired with a reflective backing. Anecdotal evidence supports this theory, as some historical accounts mention silver foil being applied to the back to increase the stone’s sparkle. Interestingly, the brilliance of the CZ replica, without any foil enhancement, supports the likelihood of a flat-backed cut in the original.
Modelling of the Spoonmaker Diamond remains complex due to variability in reported dimensions—typically 42 x 35 x 16 mm, but with possible variations of ±0.5 mm. Even a minor change of 1 mm in girdle thickness can alter the weight by several carats, making precise reconstruction difficult. Given these variations, the gem’s true weight could range significantly, especially if the girdle depth has never been officially recorded.