Black inclusion (what mineral) in diamond

[Ashleigh]

Hi all,
When one has a clear crystal inclusion in a diamond, it's most probably a diamond crystal in the diamond. But when the inclusion is dark, what mineral is it? I googled and it said uncrystallised carbon but what exactly is uncrystallised carbon? Graphite? I searched PS and realized this topic was never discussed. Interested from knowledge perspective. Not concerned about eye cleanliness here. Thanks in advance to all who can share some insight.

 

[mimi123]

Hi Ashleigh! That's an interesting question - I remember some time back reading something about it. It went something like this - diamond is formed from carbon that has been under tremendous heat and pressure for thousands of years, and it becomes crystallized. Crystallized carbon is diamond. The black inclusions are bits of carbon that were not transformed completely. Also, if I remember correctly, once diamond has been transported to the surface of the earth and is no longer under those pressures, it begins to revert back it's original composition - in other words eventually (many millennia from now) all diamond we have in our jewelery boxes, will become pencil fodder - graphite.
I'm sure someone in the know will confirm/revise my recollection!

 

[Cricketcat]

Wow, is that really true about the pencil fodder/graphite thing? I always thought 'a diamond is forever.'

 

[bcavitt]

According to my resident G.G. who is also a geologist, that unless you could magically suspend a diamond so it has absolutely no contact with anything that touches the earth's crust, the earth will at some point in time recycle the diamond into some other form. Do we care? Not in ours or in any generation we could even think about's lifetime.

Bryan Cavitt
Images Jewelers

 

[Ashleigh]

Hi Ashleigh! That's an interesting question - I remember some time back reading something about it. It went something like this - diamond is formed from carbon that has been under tremendous heat and pressure for thousands of years, and it becomes crystallized. Crystallized carbon is diamond. The black inclusions are bits of carbon that were not transformed completely. Also, if I remember correctly, once diamond has been transported to the surface of the earth and is no longer under those pressures, it begins to revert back it's original composition - in other words eventually (many millennia from now) all diamond we have in our jewelery boxes, will become pencil fodder - graphite.
I'm sure someone in the know will confirm/revise my recollection!

Hi Mimi, I read the same thing too on Wikipedia. Sounds interesting. Too bad we won't be around to watch our diamonds turn into pencils

 

[Ashleigh]

According to my resident G.G. who is also a geologist, that unless you could magically suspend a diamond so it has absolutely no contact with anything that touches the earth's crust, the earth will at some point in time recycle the diamond into some other form. Do we care? Not in ours or in any generation we could even think about's lifetime.

Bryan Cavitt
Images Jewelers

My question came about because I was thinking some ladies can claim they have a diamond crystal within their diamond, cool! I've saw one tutorial where the vendor showcased a garnet crystal within a diamond, awesome! Then I wonder what crystal I've within my diamond. Uncrystallised carbon sounds so uninspiring, hence the question.