OK. I clearly had a lapse in naming. "Phoenix-eye" is something different, and blue tiger-eye is called "hawk-eye."

Regarding my comment on the transformation from a blue color to yellow, my source is Bauer's "Precious Stones" (Vol. II p. 494, 1904). It is certainly possible that a later exposition might alter this explanation. However, I can certainly show my source. See the attached paragraph from this page of the book.

JDA.