- The Washington Times - Thursday, January 10, 2002

The Hope Diamond has passed between commoners and kings. Since about 68, the priceless blue gem exchanged hands across oceans and continents. It even survived lootings during the French Revolution. In 1958, Harry Winston Inc. of New York City donated the 45.52-carat stone to the Smithsonian Institution.But its human history pales in comparison to its natural history, says Jeffrey E. Post, curator of gems and minerals at the National Museum of Natural History of the Smithsonian Institution in Northwest.
"Its hanging around the last 300 years is pretty trivial," he says. "It was probably brought to the surface about 1.1 billion years ago in Golconda, India. Think of what it had to go through to be formed in the first place."
Before diamonds adorn numerous bodies across the world, they make their homes about 100 miles below the Earth's surface. They emerge from an intense creation process of high pressure and high temperature as the world's hardest material, Mr. Post says. Miners collect them and gemologists inspect them for flawlessness.
Mr. Post says some scientists suggest the formation of diamonds began as long as 3 billion years ago, creating diamonds at about 2,190 degrees Fahrenheit. With these extreme conditions, carbon in the Earth's upper mantle becomes a crystal structure, which comes to the surface through volcanic eruptions of about 25 mph in force.
"The explosions have to be extremely violent," he says. "If you gave the diamond a long time to reach the surface, it would turn into graphite because the atoms would rearrange themselves in the cooler temperatures and lower pressures near the Earth's surface."
Peter Heaney, associate professor of mineralogy at Penn State University in University Park, Pa., says the volcanoes that bring up diamonds occur in cratons, the oldest parts of continents, which are found in places such as South Africa, Australia, Brazil, Siberia and Canada. Since continents grow over time, cratons remain as the oldest cores of the continental land masses. Miners find diamonds there because diamond deposits are extremely old.
"The United States has areas of cratons with diamonds, but we don't have the diamond mines that rival the production of Australia and South Africa," he says. "We don't mine them because we don't have a high enough concentration of high-grade diamonds."
When the magma from the volcanic eruptions cools, it becomes kimberlite rock, a black volcanic rock with high concentrations of the mineral olivine that is named for Kimberly, South Africa, where it was first found. In time, the rock weathers away and diamonds remain. Since diamonds contain strong three-dimensional carbon atom bonds, they withstand most acts of nature, such as rain and heat. Water frequently transports diamonds to streams, creating "alluvial" or river deposits, Mr. Heaney says.
Some miners find diamonds in streambeds, but hard rock mining of kimberlite provides the primary source of diamonds. Often, explosives blast rock, and heavy equipment gathers the material. Further processing of the rock separates the diamonds from unwanted minerals.
Since scientists lack the ability to travel into the Earth's mantle, Mr. Heaney says, diamonds and the minerals associated with them provide a way for experts to learn about the depths of the Earth, especially when diamonds contain other minerals.
"People who wear diamonds as engagement rings usually don't realize that they are wearing a chunk of the Earth's history on their finger," he says.
Diamonds not only originate beneath the Earth, but also in space, Mr. Heaney says. When meteorites crash into each other or hit the Earth, organic carbon may be transformed into microdiamonds, which are as thick as a human hair. Tiny crystal diamonds or nanodiamonds also line the inside of meteorites.
"These tiny crystals are some of the oldest objects ever seen," he says. "They predate the formation of the solar system, which is believed to be about 4.5 billion years in age."
Although scientists try to replicate the formation process of diamonds in the laboratory, Mr. Heaney says their efforts failed to synthesize high-quality diamonds cheaply. For romantic sentiment, people usually want a diamond created in the depths of the Earth. The pressures required to make a diamond equal that of the Eiffel Tower standing on a penny 800,000 pounds per square inch, Mr. Heaney says.
"Synthetic diamonds are imposters and not natural diamonds," Mr. Heaney says. "They will always be worth less. Price is associated with rarity, and synthesized gemstones can be produced in great abundance. There is a mystique surrounding natural gemstones."
Stephen Haggerty, professor of geology at the University of Massachusetts at Amherst, says the same uncut, natural diamonds that would sell for about $100 could cost up to $10,000 once cut and polished.
After a sorting process at the mines, diamonds are bought by manufacturers and buyers. They send the stones to major diamond-cutting centers in places such as Antwerp, Belgium; Bombay; Johannesburg; and New York City. Most diamonds have 58 facets or smooth faces cut into them, which optimize the fire or "flash" of the gem.
"The percentage of diamonds that are mined that are high enough quality to be jewelry are a very small percentage, probably like 10 [percent] or 20 percent," Mr. Haggerty says.
It is hard to overstate the value that people place on these brilliant bits of stone. Within the past decade in places such as Angola and Sierra Leone, rebels have stolen diamonds from miners to sell to support their civil wars. Osama bin Laden's al Qaeda network is reportedly funded in part by stolen diamonds from the Democratic Republic of Congo.
Philip York, senior instructor in the Gemological Institute of America in Carlsbad, Calif., says the diamond industry uses "the four Cs" to determine the worth of the gems after they are processed by diamond-cutting centers cut, clarity, color and carats. These clarifications help jewelry wholesalers and retail jewelry stores to decide which stones to buy.
For cut, the institute evaluates the size and angle of the polished facets on diamonds. For clarity, it ranks them from "flawless," which lack impurities known as inclusions, to "included," which contain impurities.
The institute devised a color-rated diamond index, which ranges from completely colorless (D) to light yellow (Z), with colorless as the most expensive. Its Web site is www.gia.edu.
"As you go down the color scale, you have more yellow and brown and less value," Mr. York says. "Very small concentrations of nitrogen color a diamond yellow and brown."
Fancy diamonds, with intense or vivid colors, present an exception. Mr. York says fancy pinks and fancy blues lack a definite market price because of their rarity. Diamonds become blue because of the presence of the element boron. All other fancy diamonds, such as red, pink and yellow, become those colors because of changes in the crystal structure as the diamond forms.
"If you happen to like yellow diamonds, you may not be able to perceive the exact color as a retail consumer, but there may be a very big difference," Mr. York says. "It has to be an intense yellow for it to be a fancy. Always ask for a diamond quality report to tell about the diamond you are purchasing."
As a general rule, the larger the diamond, the more valuable it is, Mr. York says. One carat equals 200 milligrams.
"A diamond by nature is rare," he says. "The rarity factors of each of 'the four Cs' create the rarer and higher value."
Robert Hazen, staff scientist at the Carnegie Institution of Washington's Geophysical Laboratory in Northwest, says industrial companies use lower quality natural diamonds and synthetic diamonds as polishing and cutting tools for stones, concrete and asphalt. High-precision mass-produced parts, such as engine blocks and pistons, which use robotic machining, incorporate diamond abrasives.
"The next time you are in the dentist chair, thank synthetic diamonds for making it a less painful experience," he says. "Not that you want to go rushing off to see the dentist."

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