Rarity is one reason for the desirability of yellow diamonds but Tiffany also had a part to play. In 1878, after a year of being studied, a rough yellow diamond was cut under the supervision of a brilliant gemmologist George Kunz. This exquisite stone yielded an impressive 128.51 carat cushion cut and was to be become the emblem of Tiffany & Co. This yellow monster was on display at Tiffany on 5th Avenue for 70 years where it has had millions of admirers. At the time of cutting, Charles Tiffany was unsure of the rarity of the piece as South Africa was producing a healthy measure of yellow stones. But, in the following years, the depth of colour possessed by the emblem stone was confirmed as exceedingly rare and valuable.
So what causes a diamond to be yellow? Here comes the science…
Diamonds are made up of mainly carbon and when one has absolutely no other elements within its structure it possesses no colour and would be graded as a D.
All other diamonds contain other chemical elements, most often nitrogen. Since the nitrogen atoms do not have the same number of electrons as the carbon atoms, they bond with the carbon atoms in such a way that one nitrogen electron remains free. The free electrons are able to partially absorb light, most often the blue and violet wavelengths. The diamond’s yellow colour results from the light that has not been absorbed. The different ways in which the nitrogen atoms are present accounts for the different intensity of yellow within the diamond.
The deeper colours are rarer and thus command high prices.
How are yellow diamonds graded? I am sure you have all heard of white diamonds being referred to as a G VS1 for example. The G stands for the colour. The internationally recognized GIA colour grading scale begins with the letter D (pure white) and ends at letter Z (tinted colour). It is beyond the Z grade that the stone would be referred to as a Fancy Coloured Diamond as opposed to a White Diamond. The lower down you go in the alphabet (so the more yellow you go) the less rare and less expensive the stone is. However after colour Z this is reversed! The colour range for Fancy Coloured Diamonds includes four colour grades: Fancy Light Yellow, Fancy Yellow, Fancy Intense Yellow, and Fancy Vivid Yellow. The colour known commercially as canary or canary yellow actually refers to the GIA grade of Fancy Vivid Yellow.
Why are most yellow diamonds radiant or cushion cut?
The intensity of the stones can be clearly improved by choosing the most appropriate shape; as a result, the stone’s value will increase accordingly. The Radiant Cut and the Cushion Cut both respond beautifully to large yellow diamonds. The reason for this is that they ‘hold’ the colour well. Experience has shown that a Radiant Cut yellow diamond might be certified as “Fancy Yellow”, whereas the same stone would most probably be certified as only “Fancy Light Yellow” were it to have a round brilliant shape.
The Celebrities. There have been several celebrity yellow diamonds besides the aforementioned Tiffany stone.
The Eureka (Greek for “I‟ve found it!”) is the first recorded diamond to be found in Africa. The pale yellow diamond was found in 1866 by children playing along the Orange River in Hopetown, South Africa. Later, in 1867, the rough 21 carat diamond was officially recorded as the first authenticated diamond discovered in the history of Africa. The diamond was subsequently cut to its current 10.70 ct size and in 1967, a century after its discovery, De Beers bought the diamond and returned it to the African people. The South African government put The Eureka on display at the Kimberley Mine Museum where today it continues to bear witness to the beginnings of the country’s diamond industry.
The Incomparable is the largest faceted yellow diamond in the world. It is flawless and weighs 407.48 ct. It was found in the Democratic Republic of the Congo, supposedly by a little girl who was playing on a garbage heap next to a diamond mine. Its colour has been determined by the GIA as Fancy Brown Yellow.
The Kahn Canary is a flawless, rough diamond weighing 4.23 ct. Discovered in 1977 in the state of Arkansas, nick-named “The Natural State”, this diamond has become the state’s unofficial symbol for its natural uncut triangular form. Former First-Lady Hillary Clinton was allowed to wear the diamond on several ceremonial occasions, including the inauguration of Bill Clinton as the President of the United States of America.
Thanks to Kulsen and Hennig, the coloured diamond specialists.