This diamond grading tutorial will explain how diamond cutters create hearts and arrows patterns within round brilliant cut diamonds. The diagram provided by Brian Gavin which appears to the left, shows the pavilion facets of a diamond outlined in orange. The pavilion main facet which is located in the twelve o’clock position has been colored green. Imagine that the green color is light which is striking the pavilion main facet. That light reflects across the diamond and is split into two halves by the pavilion main facet located in the six o’clock position. Then that light reflects over on to the lower girdle facet located on either side of the pavilion main. In doing so, it creates one half of the heart shape. This process repeats itself throughout the entire facet structure of the diamond, creating the 360° pattern of hearts. Any variance in the structure or indexing of the lower girdle facets, will create hearts of different sizes, shapes, or which twist at the tips.