Jacqualina - if you read my post the other day ranting about Tony Diniz's side stepping you'll see he did very much the same. BE diffusion is not about filling per se. It's about turning a crap coloured sapphire into a pretty looking sapphire. Filling is another process.
You have to ask yourself whether you trust this company? I wouldn't trust them as far as I could throw them. I don't believe what they say, I don't believe their pricing, I can buy better gemstones at better prices and I won't deal with a dishonest company. However, it's horses for courses! If you do decide to buy a Pad from them, please contact me because I can tell you where to get it tested for BE diffusion.
As far as the gem trade goes, it's worth considering the best effort to date to try to bring some kind of standard to the topic. In April 2007, the Laboratory Manual Harmonisation Committee (LMHC), a committee with representatives from the world's leading gem labs, published a statement on Padparadscha Sapphire ("Information Sheet #4). Here are the main points:
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Padparadscha sapphire is a variety of corundum from any geographical origin whose color is a subtle mixture of pinkish orange to orangey pink with pastel tones, and low to medium saturation.
The name 'padparadscha sapphire' SHALL NOT be applied in the following cases:
* If the stone has any colour modifier other than pink or orange.
* If the stone has major uneven colour distribution when viewed with the unaided eye and the table up +/- 30 degrees
* If the stone has been treated by lattice diffusion of a foreign element, treated by irradiation or dyed, coated, painted, etc.
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