Hearts & Arrows is the pattern created on an "ideal" cut round brilliant stone. Through the top of the stone you can see the arrows pattern & through the bottom of the stone you can see the hearts pattern.
Not all well-cut stones display a perfect H&A image.
Not all stones that display the H&A image are perfectly cut diamonds.
GIA and AGS don't grade or list H&A as part of their grading report.
Excellent or Ideal symmetry from a lab report does not guarantee a crisp H&A pattern.
There is no industry standard for what passes for a Hearts and Arrows stone.
Some consider the pattern a sales gimmick, some consider the pattern to be the pinnacle of the art of cutting, some consider it a happy coincidence in a well-cut stone.