Origin of name
The diamond gets it's name from the late Sir Ernest
Oppenheimer, the former Chairman of the De Beers Consolidated Mines Ltd. and
a pioneer in the mining industry of South Africa, in whose memory the stone
was named by it's purchaser Harry Winston, in 1964, who subsequently donated
the rough diamond to the Natural History Museum of the Smithsonian
Institution, and is today one of the most prominent exhibits of the
institution.
Characteristics of the
diamond
The unique feature of this rough diamond, is the almost
perfectly formed Octahedral (8-sided), natural crystal form of the diamond,
which represents one of the common theoretical forms in which natural
diamonds crystallize. The yellow color of the diamond adds to the uniqueness
of the stone, and makes it one of the rarest natural diamond crystals in the
world. The weight of the diamond is 253.7 carats, and is the second largest
uncut diamond in the world after "the 616" which is the larges uncut diamond
crystal. When listed with other faceted yellow diamonds, the Oppenheimer is
the second largest yellow diamond in the world after the Incomparable which
weighs 407.48 carats.
History
The diamond was discovered in the Dutoitspan Mine,
belonging to De Beers, at
Kimberley, South Africa, in 1964. The perfectly formed, enormous, natural,
octahedral, yellow diamond crystal astonished it's discoverers, that they
decided to preserve it in it's natural crystalline form. The news of the
discovery reached Harry Winston, who decided to purchase it immediately
after seeing the unique rough crystal. After naming the diamond in memory of
the late Sir Ernest Oppenheimer, Harry Winston donated the diamond to the
Smithsonian Institution in order to preserve it for posterity.
It is appropriate to recall here that it was Harry
Winston, who in November 1958, donated the Hope diamond to the Smithsonian
Institution, with the primary aim of helping the institution, to build up a
major National Gem Collection for the American people. The donation of the
Oppenheimer diamond to the institution was in furtherance of his cherished
dream.
Some of the important diamonds in the diamond collection
at the Smithsonian's Natural History Museum are :-
1. The Hope diamond - A fancy dark grayish blue diamond
weighing 45.52 carats, donated by Harry Winston in November 1958. This is
the largest blue diamond in the world. The diamond originated in the Kollur
mines of Golconda in Southern India.
2. The Blue Heart diamond - A heart-shaped fancy intense
blue diamond weighing 30.62 carats, donated by Marjorie Merriweather Post in
the 1960s. The diamond originated in the premier mines of Southern Africa
and was discovered in Nov. 1908. It is the 5th largest blue diamond in the
world.
3. The Portuguese diamond - An emerald-cut, colorless
diamond weighing 127.01 carats, which strongly fluoresces blue under
ultra-violet light. Even in ordinary daylight it fluoresces slightly, giving
a bluish tinge. The diamond was acquired from Harry Winston in exchange for
2,400 carats of small diamonds. The diamond was mined in the premier diamond
mines of South Africa in 1910, contrary to what one would expect from the
name of the diamond.
4. Victoria-Transvaal diamond - A 67.89 carat, brownish
yellow, pear-shaped diamond, donated by Leonard and Victoria Wilkinson in
1977. The diamond was discovered in Transvaal, South Africa, in 1951 and
featured in a 1952 Hollywood film Tarzan's Savage Fury.
5. The Oppenheimer diamond - a 253.7 carat, naturally
formed, yellow colored, enormous, octahedral crystal, which is preserved in
it's natural rough state. The diamond was discovered in 1964 in the
Dutoitspan mine in Kimberly, South Africa, and was purchased by Harry
Winston and donated to the institution.
6. Smithsonian Canary yellow diamond - This a rare,
unique, canary yellow, sparkling, round brilliant-cut diamond, mounted on a
ring.
The collection also includes some renowned items of
diamond jewelry such as :-
1. Napoleon I diamond necklace - This is a 275-carat
diamond necklace given by Napoleon I to his consort Empress Marie Louis in
1811, to celebrate the birth of their son and long desired heir, Napoleon
Francois Charles Joseph Bonaparte also called the King of Rome, or
Napoleon II.
2. Crown of Empress Marie Louise - This crown was given
by Napoleon I to his consort Empress Marie Louise and was set in silver with
950 diamonds weighing 700 carats, and 79 emeralds. (The emeralds are now
replaced by turquoise cabochons).
3. Marie Antoinette earrings - Two diamond earrings that
belonged to Marie Antoinette, Queen consort of King Louis XVI, confiscated
from the Queen during the French Revolution.
4. Spanish Inquisition Necklace - This is a diamond and
emerald necklace belonging to the Spanish Inquisition period.
Chemistry of the diamond
Diamonds are up to 3 to 4 billion years old formed deep
inside the earth about 200 Km below the surface in the earth's mantle. The
crystals then gradually rose to the surface of the earth along lamproite and
kimberlite pipes, which acted like conduits from the earth's mantle to the
surface crust.
Diamonds are crystalline forms of Carbon, in which each
Carbon atom is surrounded by four other equidistant carbon atoms at the
corners of a regular tetrahedron. These units are repeated over and over
again in the face centered cubic pattern, crystallizing in the isometric
crystal system, resulting in octahedral or cubic crystal forms commonly
found in natural diamonds. Sometimes dodecahedral forms have also been found
in naturally occurring diamonds. The Oppenheimer diamond has crystallized in
the octahedral form.
The diamond has not been color graded as it was not cut
and polished, but the color appears to be an intense yellow color. Yellow
color in diamonds is caused by the presence of trace quantities of
nitrogen impurities (less than 0.1 %), in the crystal structure. 98 % of all
naturally occurring diamonds contain nitrogen impurities and are known as
type I diamonds. But, the yellow color is determined by the concentration
and distribution of the nitrogen atoms inside the crystal. The most intense
yellow colors such as the rare canary yellow colors are produced when
nitrogen atoms are scattered as single atoms in the crystal structure. These
nitrogen atoms absorb visible light in the blue end of the spectrum,
producing the intense yellow colors. These diamonds are known as type Ib
diamonds, but are rare and constitute only about 0.1 % of all naturally
occurring diamonds.
Other shades of yellow colors are produced when nitrogen
atoms are found in groups of three atoms known as N3 centers. These centers
can also absorb visible light in the blue end of the spectrum imparting
different shade of yellow colors depending on the concentration of N3
centers. If nitrogen atoms are scattered as groups of two atoms (A-groups),
or four atoms (B-groups), they do not affect the color of diamonds as these
groups do not absorb visible light. These diamonds are known as type Ia
diamonds which constitute almost 98 % of natural diamonds. Type Ia diamonds
are sub-divide into three types :-
Type IaA - Nitrogen atoms found as A-groups. Diamonds are
colorless.
Type IaB - Nitrogen atoms found as B-groups. Diamonds are
colorless.
Type IaAB - Nitrogen atoms found as A-groups, B-groups,
and N3 centers. Diamonds have different shades of yellow color. A great
majority of type Ia diamonds belong to this sub-group.
Thus the Oppenheimer diamond is most probably a type IaAB
diamond.
List of famous yellow
diamonds
|
S/N |
Name |
carat weight |
shape/cut |
color |
|
1 |
Incomparable |
407.48 |
shield shaped |
fancy brownish yellow |
|
2 |
Oppenheimer |
253.70 |
natural octahedral |
yellow |
|
3 |
De Beers |
234.65 |
cushion |
light yellow |
|
4 |
Red Cross |
205.07 |
cushion |
canary yellow |
|
5 |
Florentine |
137.27 |
double rose-cut |
light yellow |
|
6 |
Sarah |
132.43 |
cushion |
fancy vivid yellow |
|
7 |
Tiffany Yellow |
128.54 |
cushion |
canary yellow |
|
8 |
Vainer Briolette |
116.60 |
briolette |
fancy light yellow |
|
9 |
Mouna |
112.50 |
cushion |
fancy intense yellow |
|
10 |
The Alnatt |
101.29 |
cushion |
fancy vivid yellow |
|
11 |
Walska |
95.00 |
briolette |
yellow |
|
12 |
Shah Diamond |
88.70 |
table |
yellow |
|
13 |
Porges |
78.53 |
asscher |
fancy yellow |
|
14 |
Victoria Transvaal |
67.89 |
pear |
brownish yellow |
|
15 |
Peacock |
20.65 |
radiant |
fancy intense yellow |
|
16 |
Shepard |
18.30 |
cushion |
fancy intense yellow |
|
17 |
Eureka |
10.73 |
cushion |
brownish yellow |
