Swiss Blue large stone

I’m trying to determine the price of a 66.35c Swiss Blue Topaz cut in a pear shaped stone. I’ve already determined that it is in fact a real, natural topaz, not a synthetic. Any help beyond the “$3-$20/ct” would be greatly appreciated. I also have a grading from a reputable source and pictures if you’d like.

Hi, as you would know swiss blue topaz is irradiated and heat treated, I really do not think that there is much difference in the price whether the gem is 20 cts or 66 cts when treated in this way. However a natural gem is totally different in price as the carat weight as it goes up in size… I would think that 15 to $20 per carat would be a fair asking price for these types of Topaz, just my opinion though