Friday, May 27, 2011

A Story of Diamonds: The Inside Scoop

Carbon crystallizes in two forms: diamond and graphite. How can these very unlike things both be crystalline carbon? It's the way the atoms are arranged. In a diamond, each carbon atom is linked to four more creating a very strong crystal. The carbon in graphite link together and form sheets which is why graphite is so slippery.



Diamond forms in the cubic crystal system which manifests in a number of growth forms. The following rendering shows the typical arrangement of carbon in a diamond crystal. Each cube represents the basic carbon structure pictured above.



Octahedron: The most common form the diamond crystal assumes. This mimics the rendering above. Generally suitable for finishing.



Dodecahedron: Similar to the octahedron, but without the points. Look at the rendering and remove the corners. Also generally suitable for finishing.



Cube: Again, look at the rendering and you will see that if you clip off the points more severely than the dodecahedron, you are left with a cube. The vast majority of these are put to industrial use.



Sometimes a crystal gets turned around, so to speak, while forming. Have a look at that diamond octohedron above. Slice it in half along a diagonal and twist it 180 degrees. You now have a macle. Many of these wind up finished in triangular shapes.



Growth conditions can cause uneven crystal face development. Large diamond crystals are often strange shapes, like this 507 carat rough crystal:



It sold at auction in 2010 for $35 million.

10 comments:

Cat said...

Interesting read again!

Jeanne/J3Jewelry said...

If I were that guy holding that HUGE diamond, abnormal growth or not, I'd be having a wide grin on my face too! I just love diamonds...they are so sparkly, and I love sparkle. I think one of my most favorite shades of blue is the blue in diamonds. It just seems so unique, I can spot it right away. I'm loving the education in diamonds!

BeadSire said...

Fascinating read and I love the graphics to accompany the post

DawninCal said...

I am learning so much about diamonds from this series - great stuff!

Jeanne, maybe that guy is grinning because he's thinking about the $35 million. $35 mil would make me smile too!

Bonnie said...

Diamonds are too rich for this jewelry maker but i loved learning about their development. Thanks.

galadryl said...

Very informative and interesting. Especially with the graphite.

EleganceandSparkles said...

Great article!

MmeMagpie said...

Diamond prospectors have found, in some locations, perfect little octahedrons of graphite in kimberite. Something about the temperature or pressure wasn't quite right and the carbon rearranged itself in the easier pattern of graphite.

StudioDTQ said...

Another really cool article. Love diamonds and it's neat when you know the origins of things-Thanks!!!

tjrjewellery said...

Interesting article1