|A oval cut topaz that is likely irradiated to produce the 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.
This is a first rate example of a poorly cut native stone! It is the typical "pineapple" pavillion, with bad angles (cut to shallow) that produces a fisheye effect in the stone.