I would not trust anything you see on the iBlueWater site. The owner doesn't have the best track record in terms of delivering what was promised. The site hasn't changed in years and has some interesting items (pink gigantea, $320 rainbow BTA called a "Orange Sunburst" and a $325 green BTA).
To answer your question, I have not seen a bright blue BTA as shown in the photo (which appears to be heavily Photoshopped). Sometimes shermans can come across as having a blue center when they're under a lot of blue light.