I have also heard that the black diamonds now in the marketplace are
irradiated, the black color hiding all the inclusions. Thankfully I
have no first hand experience to prove this, but I have also heard
that heating these can alter the color and make all the inclusions
jump right out. Another theory I don't want to test is that stones
that are this badly included don't need to be heated to begin with.
I have had to set a few, as they seem to sell fairly well in our
area, and I am wary of that, too. The inclusions are not readily
visible when setting, so I think it would be all too possible to do
some serious damage by putting too much pressure in the wrong spot,
pressure that would not normally be a problem in a decent diamond.
Jim in the mountains of NC where the rainy season seems to have
settled in to stay for a while.