Which among the following waves are used in the gemstone industry to change white topaz into blue topaz?

Q. Which among the following waves are used in the gemstone industry to change white topaz into blue topaz?
Answer: Gamma Rays
Notes: Gamma rays is commonly used in gemstone industry to change white topaz into blue topaz. Because white topaz is heat-treated to turn into blue topaz, the value of blue topaz is often decreased.