Irradiated/HPHT Diamonds

[LD]

I apologise if this is in the wrong place of the forum but I wasn''t sure where it should be! Two questions .....

(1) Is it possible to irradiate or HPHT diamonds to become a brown/cognac/champagne or are these mostly natural? My understanding is that these are fairly cheap to buy so why put the diamonds through an expensive process when naturals are readily available. However I read the other day that a brown diamond somebody had bought was irradiated so I''m confused!

(2) Also, why is it difficult to achieve a pink or red diamond using the irradiated/HPHT process but blues/greens can be produced fairly easily?

 

[amzaitsev]

Hallo!
1. Yes, it is possible to produce brown-orange-champagne color by high energy light ion irradiation and subsequent annealing at temperatures 500 to 700C. However, it is an expensive treatment. I never heard that it was used for gem diamonds. HPHT treatment does not produce orange, may be some champagne, but never brown. Although, HPHT is too expensive for such a dull colors.
2. Bluish and green colors can be easily achieved by standard electron irradiation, which is a cheap and simple technology.