Gemesis to market CVD 'colorless' diamonds.

[denverappraiser]

Gemesis, the Sarasota, Fla.–based “cultured” diamond producer that has until now manufactured mostly fancy colored stones, tells JCK it has been mass producing colorless gems for the last few months and will soon bring them to the market.

Full story here:
http://www.jckonline.com/2010/11/22...-to-mass-produce-lab-grown-colorless-diamonds

 

[iota15]

Wow.

 

[Garry H (Cut Nut)]

The funny thing is that making brown diamonds with CVD and turning them into white diamonds with HPHT and annealing is called "treatment" if you begin with natural mined diamonds.


Natural mined brown diamonds probably cost less than synthetic CVD brown diamonds cost to make.
But treating CVD diamonds is considered a natural value adding process, where as GE never managed to convince us that treating natural diamonds was 'natural'
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[EEFranklin]

Very valid point, Garry. I'd be interested to see if grading labs disclose color treatment on CVD diamonds.

 

[Garry H (Cut Nut)]

Very valid point, Garry. I'd be interested to see if grading labs disclose color treatment on CVD diamonds.

Hi Eric, Browns cost about 1/3rd the price of H (rough rule of thumb). what do you think would be the cost of making a CVD brown?

 

[EEFranklin]

Hi Eric, Browns cost about 1/3rd the price of H (rough rule of thumb). what do you think would be the cost of making a CVD brown?

I don't have any firsthand knowledge on CVD costs, so for accurate information you would have to ask Apollo or Gemesis. To grow a brown CVD diamond, I would roughly guess it costs 50-75% the price of a mined H. The diamonds then have to be pre-cut, HPHT color treated (to turn them near-colorless brownish-white), then polished.

For the record, we make white diamonds through HPHT growth but it is a different process from HPHT color treatment. Our white, blue and yellow diamonds are as-grown and not treated in any way. Our near-colorless usually have slight hints of yellow or blue, not brown.

 

[stone-cold11]

What causes the brown in a CVD diamond?

 

[EEFranklin]

What causes the brown in a CVD diamond?

It comes from defects in the crystal lattice of the carbon atoms. The HPHT color treatment 'heals' some of the defects, improving the color.

 

[stone-cold11]

Thanks, now I remember.