Amsterdam's magnificent diamond legacy | Part III

Martin Coster was the son of Moses Coster, and from 1851 he was based in Paris where he set up a hugely successful diamond polishing factory which soon achieved close to monopoly status. In addition to his business activities Coster was appointed Consul General to the Netherlands by King Willem in 1868.

This was the era of influential international exhibitions and at the Paris Exposition Universelle of 1867 a replica of Coster Diamonds’ Amsterdam workshop was exhibited, and it was incredibly popular attraction. Coster lived in Ville-d’Avray, on the outskirts of Paris, the painter Jean-Baptiste-Camille Corot was also a resident and the area inspired several of his works created in the 1860s.

Coster’s final resting place is Montmartre cemetery where his tomb is topped with a stone beaver – symbol of persistence and hard work – accompanied by the maxim HONESTAS OPTIMA POLITIA.

Two diamonds sourced from the Jagersfontein Mine, South Africa, ‘Excelsior’ in 1893 and ‘Jubilee’ in 1895, demonstrate the differing approaches at the time to extremely large, valuable stones and how they should be cut to appeal to potential buyers.

The ‘Excelsior’ rough weighed 995.20 carats, with a blue-white tint, and when discovered it was the world’s largest gem quality rough diamond. On the day it was found the contract between the mine and the syndicate which took its output had expired. The stone was shipped to the offices of Wernher, Beit and Company in London, one of the syndicate members, with the mine retaining a 50% share, although perhaps because of uncertainty around the legal situation the stone was not reported in the press.

The ‘Jubilee’ rough weighed 650.80 carats, it was named in honour of the forthcoming Diamond Jubilee of Queen Victoria in 1897, and for some reason it overshadowed ‘Excelsior’ which was possibly deemed too large and magnificent.  

In 1903 ‘Excelsior’ was sent to I J Asscher in Amsterdam and was cut into 11 stones, Abraham Asscher, the grandson of the firm’s founder cleaved the stone. The Excelsior I-XI stones ranged in weight from 69.68 to 9.82 carats, a mix of pear and marquise cuts, along with 11 smaller stones some of which weighed a fraction of a carat, and Henry Koe (1870-1928) from Asscher was the polisher. The final total weight amounted to 373.75 carats, a loss of 63%, but it is not clear why there was no attempt to create one large stone. Tiffany initially bought three of the stones, and in 1939 De Beers displayed one of the marquise-shaped Excelsior diamonds at the World’s Fair, held in New York. Excelsior I was bought in 1996 by Robert Mouawad.    

A year after its discovery ‘Jubilee’ also went to Amsterdam where M B Barends of Metz worked on it. The removal of a 40-carat piece resulted in a 13.34 carat pear-shaped diamond, which was purchased by Carlos I of Portugal, with the final E-VVS2 cushion-shaped stone weighing 245.35 carats. Its first owner was Dorabji Tata (1859-1932), the son of the founder of the Tata Group, who bought for his wife, Meherbai, and she wore it frequently. When ‘Jubilee’ was sold in 1932 the sale proceeds went towards the formation of the Sir Dorabji Tata Trust, and since then ‘Jubilee’ has joined ‘Excelsior’ in the collection of Robert Mouawad. 

The diamond industry in Amsterdam was virtually destroyed during the second World War and although some firms started up again in the city once the fighting was over, work for the most part was to move for good to Antwerp, Israel and India.