Allnatt diamond

The Allnatt's origins are unknown prior to Major Allnatt's purchasing of the diamond in the early 1950s. After purchasing the diamond, he commissioned Cartier to make a setting for it. The final setting was a platinum flower with five petals, a stem and two leaves, all set with diamonds. After being sold to the SIBA Corporation, the diamond was re-cut to its current weight and the intensity was upgraded as a result.

The rare color grading for a diamond of this size was done by the GIA. The full report is even more impressive - 101.29 carat Fancy Vivid Yellow Diamond with VS2 clarity. The high clarity grading is exceptionally rare when it comes to such oversized diamonds.

The Allnatt diamond was named after its first known and recorded owner - Alfred Ernest Allnatt, an English businessman and philanthropist. Even though the source of the diamond is unknown, different experts tend to attribute it the De Beers Premier Mine in South Africa. This is simply because the diamond carries some of the same characteristics of other diamonds from that area.

The Allnatt was bought by Alfred Ernest Allnatt in 1950 and was brought to Cartier for setting. It was mounted into a beautiful pin made of platinum in the shape of a flower. The flower had five petals, a stem and two leafs where everything but the Allnatt Diamond was set with white diamonds (see image below).

The Allnatt was presented in the Smithsonian museum as a part of the famous sublime diamond exhibition splendour of diamonds, along side the Millennium Star, Heart of Eternity, Moussaieff Red and Steinmetz Pink. The last time this diamond was sold was at a Christie's Auction back in May 1996 and it was bought by SIBA corporation for the amount of over $3,000,000.

The Allnatt diamond is a 101.29-carat, cushion-cut, fancy vivid yellow diamond with a VS-2 clarity, as certified by the Gemological Institute of America. Fancy vivid is the highest color grading that can be given to colored diamonds in the GIA color grading scale.

Being a fancy vivid yellow diamond, the Allnatt is without any doubt a Type Ib diamond, in which the intense yellow color is produced by nitrogen atoms scattered as single atoms in the crystal structure. These nitrogen atoms absorb visible light in the blue region of the spectrum, causing the complementary color of blue, which is yellow, to manifest itself. However the occurrence of these diamonds are only about 0.1 % of all naturally occurring diamonds, and are therefore quite scarce.

Type Ia diamonds on the other hand, have an occurrence of almost 98 % in nature, and a great majority of natural diamonds belong to this group. These diamonds vary from near colorless to pale and medium yellow colors. Nitrogen atoms in these diamonds are found as groups of 2, 3 or 4 atoms. If found as groups of 2 or 4 atoms they do not affect the color of diamonds. However if nitrogen occurs as groups of 3 atoms, known as N3 centers, it can impart a pale to medium yellow color to the diamonds, depending on the concentration of the N3 centers. Usually groups of 2, 3, and 4 atoms occur together in the same crystal, and such diamonds are known as Type IaAB diamonds.