|A whirlpool cut topaz (by author) that is a pale blue color. There are many "unofficial" names for the blue, "sierra blue", "london blue", "electric blue", etc. They are said to refer to the shade of blue produced. They are marketing names and not defined by a true particular color.
It is unknown whether or not the rough for this stone was irradiated or not. It is not unusual for rough as well as finished stones to be irradiated to improve color.