Natural fancy yellow diamonds are extraordinarily rare, exclusive and expensive.
They belong to an exclusive group of extremely rare natural colored diamonds occurring in nature in myriad colors.
The
usual perception is that a diamond is a colorless (or white) stone. In
fact most diamonds are indeed colorless. Nevertheless, a tiny percentage
of these gemstones acquire particular shades of colors. This depends
upon certain sets of atmospheric conditions existing in the vicinity of
the diamonds during their formative years.
How does a yellow diamond become yellow?
A
diamond is a crystallized isotope of carbon. The majority of natural
diamonds develop in high pressure & high temperature conditions.
Such conditions exist at extreme depths of 140 to 190 kms inside the
Earth's Mantle. Carbon or carbon containing minerals provide the seed
carbon source. The metamorphic crystallization of the carbon into a
diamond happens over a period of hundreds of millions of years. This is
nothing short of a miracle.
Purer carbon seed & near perfect
crystalline lattice structure yield clearer & colorless diamonds.
Yet, the conditions in which a diamond develops are far removed from the
ideal and sanitized conditions of a laboratory.
At times the
crystalline structure of the diamond gets distorted by the immense
pressure at those depths. At other times, the seed carbons source gets
impregnated with impurities like nitrogen, boron or hydrogen. Many a
times such factors occur simultaneously.
Depending on the type of
impurity (or crystalline distortion), the resulting diamond absorbs
certain spectrums of light and reflects others. We perceive the color of
the diamond based on the reflected spectrum of light.
The most
common impurity element found is nitrogen. Nitrogen atoms have an
unequal number of electrons than carbon. When both of them bond, one of
the nitrogen electrons remains unattached. These free electrons in orbit
around the nuclei partially absorb blue & violet light wavelengths.
The wavelengths which are not absorbed appear yellow to the human eye
thus giving the diamond its yellow coloration. Nitrogen impurities
impart the yellow color to a diamond.
Overall, natural colored
diamonds are extremely rare. However, among the elite group of natural
colored diamonds, yellow diamonds are the most common. Among the 100
largest diamonds in the world, one third of them are yellow. The most
famous being The Kimberley Octahedron, weighing massive 616 carats.
Natural
fancy yellow diamonds should not be confused with the transparent (or
white) diamonds of inferior quality. They too, happen to appear pale
yellow on account of presence of trace nitrogen impurities. The color
grades of white (transparent) diamonds range from D to Z. Grade D
diamonds are the whitest/clearest and most valuable, while grade Z are
tinted with faint sickly yellow to brown and are least valuable in
comparison.
A diamond with stronger yellow going beyond the Z
color grade confers the coveted fancy yellow grade upon the diamond.
Such a diamond is highly sought after by the celebrities, the royalties,
the fashion forward, and the jewelry designers. The diamond becomes
pretty expensive and goes beyond the reach of most of us.
As the
diamonds become progressively darker yellow in color, they are given
their own separate color grades like fancy light yellow, fancy yellow,
fancy intense yellow and fancy vivid yellow (also known as canary
yellow).
Like all natural colored diamonds, the deeper and more
intense the yellow in a yellow diamond the higher the value of the
diamond will be. A tiny.25-carat yellow diamond can be priced as high as
10,000 dollars depending on its clarity and cut. Larger 6 carat Fancy
Vivid Yellow diamonds have been sold for as high as $57.000 per carat.
All yellow diamonds look more intense once set in yellow gold.
Similar to white diamonds, the 4C's
namely color, cut, clarity and carat are the factors that need to be
considered before choosing a yellow diamond. With Colored Diamonds,
Clarity is not as important as Saturation of Color and their prices
depend on saturation of color. A diamond must be certified by a
gemological laboratory to be called natural.
Radiant and cushion
cut work well with large, yellow diamonds because of their
predisposition to hold color well. Using one of the round cuts has been
known to lower the intensity of color by a full grade in certain cases.
The
Argyle mine in Western Australia is the most prolific producer of
yellow diamonds followed by diamond mines in South America and South
Africa. Around one in every 1000 diamonds mined is a fancy colored
diamond.
