it is interesting in the treating of topaz. there is heat treating and radiation treating. no problems in heat treated accept that the colors are not natural and in some cases the colors may fade down or away. i gave my cousin a 35 carrat cut white topaz and he got it irradiated at hanford. it was double checked for radioactive content and safety and was very fine and safe. it turned out VERY dark champagne pink and not very brilliant. i took it to and alcohol flame and it started fading back till it was about medium color and the brilliance was there. it has never gotten any lighter in color. some of the rough from Utah and texas and colorado have had natural earthy radiation and when exposed to sun light some do fade to colorless. i have topaz that came out of brazil during the 1930-45 and has not been treared in any way and may be treatable. i do not believe in treating stones to change color true and natural is the way nature created it and i leave it that way. i cut stones that show any signs of color directly down the C axis tipped 5 degrees, this will bring out any color. gemmakermz@cs.com