This article is from Forbes.
Life
Colored diamonds, nature's most gorgeous
collectible, are beginning to catch more
light.
Aurora borealis in a rock
By Robert Goff
Colored diamonds get a bad rap. To the
uninitiated, a pink diamond is the gem
world's equivalent of a spray-painted
striped carnation—a garish, vulgar
abomination. This prejudice is not without
reason. Third World nuclear facilities just
love turning out fake colored diamonds by
bombarding colorless diamonds with atoms
that change their molecular structures (see
"Hard science").
There's a reason why these Third World
nuke plants consider this lily-gilding
endeavor a valuable use of their molecular
energy: It's because real colored diamonds
produced by nature's cunning hand are so
very rare and so very beautiful. And so very
expensive (see "The color of money").
The rarest of all colored diamonds—the
blood-red diamond—is to a ruby "what wood
is to formica," in the words of Simon Teakle,
head of Christie's jewelry department. When
collectors come across one—which is not
very often—they must pony up close to $1
million to buy it. (Oh, by the way, that's $1
million a carat.)
For the past 18 years, Alan Bronstein, 43,
and collector Harry Rodman, 90, have
scoured the earth to assemble a
colored-diamond collection. Called the
Aurora Collection, it consists of 260 gems in
an astounding palette of colors like apricot,
china red, honey, rose, ink blue, kelly green
and jonquil.
On Mar. 27 their collection, on loan for the
past decade to New York City's American
Museum of Natural History, became the
centerpiece of "The Nature of Diamonds"
exhibition at the San Diego Natural History
Museum, where it will remain on view until
Sept. 7.
It's a good introduction to a fascinating
corner of the gem world. This collection
isn't about the size of its gems, which range
from 0.13 to just 2.88 carats for a total
weight of 231.78 carats. (The Hope
Diamond alone is 45.5 carats.) The pleasure
of the Aurora Collection comes in seeing the
enormous variety of brilliant hues play off
one another—an entire aurora borealis
locked in each rock.
Consider that for every 10,000 colorless
diamonds, there is only one gem-quality
("fancy" in the lingo of professionals)
colored diamond. Last year Australia's giant
Argyle diamond mine, a relative mother lode
of pink diamonds, yielded a mere 40 carats
worth of the rarest pink gems from a total
of 39.2 million carats of diamonds mined.
The scarcity of colored diamonds is due to
the extreme infrequency of the fragile
geologic conditions necessary to paint a
hue on a colorless rock. Each diamond in
the Aurora Collection has a different story
to tell of how it got its color. Canary yellow
diamonds, for example, occur when nitrogen
atoms replace isolated carbon atoms. This
is no everyday event: It only happens when
the stone is exposed to temperatures of
roughly 1,300 degrees Celsius during a
prolonged volcanic ascent.
That's positively banal, though, compared
to what the green diamond goes through.
These extremely rare diamonds look black
before they are cut because they get their
color from exposure to uranium-rich ore
over millions of years. And what causes the
pink ones remains a complete mystery. |
