I dont have access to specific information about the grade of Turkeys Onyx Travertine. However, I can tell you that the quality of a travertine stone is determined by its hardness, consistency, color, and overall appearance. The stone industry typically grades travertine on a scale of A to D, with A being the highest quality. Its possible that Onyx Travertine from Turkey could be graded in this way, but without specific information, it is difficult to say for certain.