Skip to content

Diamonds or graphite

By Tim Perry Diamonds are the hardest natural substance known to man, the best conductor of heat, and one of the most intriguing minerals.


By Tim Perry

Diamonds are the hardest natural substance known to man, the best conductor of heat, and one of the most intriguing minerals. 
“Diamonds are the super mineral of the world,” said Mia Boiridy, director of Dynamic Earth who is showcasing some of the rare minerals at the facility in Sudbury.
“They have fantastic properties, they have the hardness, they have the thermal conductivity, they are not electrically conductive (and) they have high refraction.”
Boiridy said this makes diamonds very useful in industrial applications, and this also makes them very beautiful.
Boiridy said Canadian diamonds are among the most valuable in the world, and this is due to their quality.
“If you look at a diamond that comes from Australia, they’re usually rated at about $75 (US) per carat,” Boiridy said. “So when you look at Canadian diamonds it’s generally around $100 to $125 (US per carat), so they’re on the higher end.”
Diamonds from northern Ontario’s Victor Mine have an even higher rating of $400 (US) per carat.
Boiridy said, clarity, size and colour are what determine diamond quality.
Diamond colour can be determined by impurities in the diamond, such as nitrogen, resulting in a yellow hue, and boron, resulting in a blue hue.
Another factor in diamond colour is radiation, which can give the diamond a green skin, however only the diamond's surface is green. Some diamonds are green throughout, however this is very rare.
A third way a diamond is given a colour is through “plastic deformation,” which is when the standard crystal structure of a diamond is distorted. This distortion creates a pinkish hue and happens deep in the earth where diamonds are formed. These colours were oftentimes determined as the diamonds formed.
“Diamonds were formed billions of years ago and millions of years ago they came up to the surface,” Boiridy said.
Diamonds arrived on the surface in kimberlite eruptions travelling 30 kilometres-an hour. Any slower and they tend to turn into graphite. This is because of the small margin of error in the formation of diamonds.
“Diamonds are not the stable form of carbon under surface conditions,” Boiridy said. “Diamonds only form in a very small window of pressure and temperature conditions, you usually need a lot of really high pressure, but relatively low temperatures.”
In any other circumstances the diamond would become graphite. The kimberlite eruptions preserve the diamonds and prevent them from turning into graphite.
On the surface of the planet, diamonds are metastable, which means that while it is stable and unchanging, a slight nudge in the right direction could cause it to destabilize and, in this case, become graphite. Because of this, diamonds, like the ones on jewelry, slowly convert into graphite over time, however this generally takes thousands of years.
While natural diamonds were formed millions of years ago, they are also being formed today by humans.
Modern technology has allowed the conditions for diamond formation to be reproduced in a laboratory, creating synthetic diamonds.
Synthetic diamonds are identical to natural diamonds in every way, the only difference is where they come from.
Due to the rarity of natural diamonds, they tend to be quite expensive.
Boiridy said the hope of synthetic diamonds is the ability to produce them cheaply for industrial applications.
“Right now (the cost) is the impediment in using diamonds in any kind of computer applications or thermal conductors or what have you, it’s just too expensive,” Boiridy said.
Recently the market for synthetic diamonds has crossed over into the jewelry industry, and Boiridy said the market’s reaction will all depend on what the consumer wants, while some might prefer a natural diamond, others might prefer a synthetic diamond.
The Diamonds exhibit will close in Sudbury on New Year’s Day 2010 and will be travelling across Canada, making stops in Edmonton and Halifax. Many spots are still open.