Black pearls have always been admired for their beauty and rarity. To call them "black" is slightly misleading, as in fact, being produced by nature, they are all a little different and vary from dark grey/black to aubergine with wonderful green or purple overtones. The oyster producing most of the black pearls, that are found off of the Mexican coast, is the Pinctada Margaritifera, which is best known for its black, dark grey and gun metal coloured pearls. The degree of "blackness" is due, in part, to the colour of the shell as well as the black organic substance in the pearl.

The early Spanish merchants to the area found it much easier to sell fine white pearls in Europe and it was not until the second half of the nineteenth century that black pearls grew in popularity. This was principally due to Empress Eugénie, wife of Napoleon III (married 1853), who developed a taste for these exotic gems. In the sale of her jewellery at Christie's in 1872, a black pearl necklace sold for £4,000 ($20,000), a huge sum in those days. Very few black pearl necklaces have been sold in recent years, the most famous being the three-row Nina Dyer necklace, that consisted of 151 pearls and sold at Christie's Geneva in November 1997 for $913,000.

The present necklaces are both very long and consist of seventy and sixty pearls and also have the advantage of having clasps signed by Cartier and Janesich, two of the most respected jewellers of the inter-war years. To offer for sale two matching black pearl necklaces of such great quality is indeed remarkable.