Remarkable Facts of Diamonds

All diamonds are at least 990,000,000 years old.

Many are 3,200,000,000 years old (3.2 billion years)!!!
How do we know this?
Age: from Carbon dating? NO! C-dating only works for very young carbon. You need to use other radioactive decay schemes (e.g., uranium-lead) to date inclusions in diamonds. Inclusions used for dating are around 100 microns in diameter (0.1 mm).

Diamonds are formed deep within the Earth: between 100 km and 200 km below the surface.

Diamonds form under remarkable conditions!

• The temperatures are about 900 - 1300 C in the part of the Earth's mantle where diamonds form.
• The pressure is between 45 - 60 kilobars. (kB)

• + 50 kB = 150 km = 90 miles below the surface
• + 60 kB = 200 km = 120 miles below the surface

Diamonds are carried to the surface by volcanic eruptions.

• The volcanic magma conduit is known as a kimberlite pipe or diamond pipe.
  
  
  
  
  We find diamonds as inclusions in the (rather ordinary looking) volcanic rock known as kimberlite.
  
  
• NOTE: The kimberlite magmas that carry diamonds to the surface are often much younger than the diamonds they transport (the kimberlite magma simply acts as a conveyer belt!).

* Diamond is made of carbon (C), yet the stable form (polymorph) of carbon at the Earth's surface is graphite.

* To ensure they are not converted to graphite, diamonds must be transported extremely rapidly to the Earth's surface.

• It is probable that kimberlite lavas carrying diamonds erupt at between 10 and 30 km/hour (Eggler, 1989). Within the last few kilometers, the eruption velocity probably increases to several hundred km/hr.

Diamond is the hardest material.

• Diamond is the hardest gem on the MOHS harness scale and graphite (also made from carbon atoms) is the softest! Given that both diamond and graphite are made of carbon, this may seem surprising.
  
  
• The explanation is found in the fact that in diamond the carbon atoms are linked together into a three-dimensional network whereas in graphite, the carbon atoms are linked into sheets with very little to hold the sheets together (thus the sheets slide past each other easily, making a very soft material).

* Diamonds are found in many localities, both overseas and in the US.

What is GIA?

GIA discovers (through GIA Research), imparts (through GIA Education), and applies (through the GIA Laboratory and GIA Instruments) gemological knowledge to the public. With 1,200 employees, the Institute’s scientists, diamond graders, and educators are regarded as the world's foremost authorities in gemology.

Internationally, the Institute has distinguished itself as the preeminent source of gemological knowledge and professionalism. The GIA Diamond Grading Report and the GIA Diamond Dossier® are considered to be the world's premier credentials of diamond quality. Many retailers provide diamond certification, however no report is as unbiased and complete as a GIA diamond grading report. Diamonds of all shapes and sizes are sent to the Institute from every corner of the globe for diamond grading and analysis.

Some famous diamonds have been graded by GIA including the Hope Diamond (45.52 carats), the Steinmetz Pink (59.60 carats), the Taylor-Burton (69.42 carats), the Allnatt (101.29 carats), the De Beers Millennium Star (203.04 carats), the Centenary (273.85 carats), and the Incomparable (407.48 carats).

GIA is the creator of the revolutionary 4Cs of diamond value (carat, color, clarity, and cut). It is also the birthplace of the International Diamond Grading System™. Today, GIA’s D-Z color-grading scale, Flawless–I3 clarity-grading scale and Excellent-to-Poor cut-grading scale are recognized by virtually every professional jeweler and savvy diamond buyer in the world.

How does pavillion depth affect a diamond's cut?

The distance from the bottom of the girdle to the culet is the pavilion depth. A pavilion depth that’s too shallow or too deep will allow light to escape from the side of the stone, or leak out of the bottom. A well-cut diamond will direct more light through the crown.

History of Diamonds

Diamonds are the hardest substance known on Earth. They make sparkling jewelry as well as saw blades that can cut through pretty much anything. Diamonds form deep within the Earth's mantle layer from the element carbon that is under huge amounts of pressure from the load of rocks above.

Recently, scientists studying diamonds have found the ages of thousands of diamonds from Southern Africa, where most diamonds are found. They discovered that there were only three times during Earth’s history when diamonds were made and that Earth no longer makes diamonds like it used to. “Something was different then. Perhaps the planet was hotter on the inside, or the composition of the rocks was subtly different. Whatever it was it has changed now,” stated Steve Shirey, one of the project scientists.

The oldest diamonds were made 3.3 billion years ago when Earth was rather young. The second time diamonds were made was 2.9 billion years ago. The scientists think that these diamonds were probably formed from rocks that lay at the bottom of a shallow sea. The carbon that made these diamonds probably came from ancient sea life. The youngest diamonds on Earth are 1.2 billion years old although a few smaller diamonds are about 100 million years old.

Some people like diamonds because they are pretty, rare, or expensive but Dr. Steve Shirey has a different view. “I think of diamonds,” he said, “as being tiny time capsules that encase a little piece of rock protecting it for billions of years and providing us with a unique window on ancient times.”