The ornamental design for flash cut gemstone arrangement, as shown and described.
FIG. 1 is a top view of a gemstone arrangement according to an embodiment of the invention;
FIG. 2 is a top view of a gemstone arrangement according to another embodiment of the invention;
FIG. 3 is a side view of the gemstone arrangements shown in FIG. 1, the side view of FIG. 2 being a mirror image;
FIG. 4 is a bottom view of the gemstone arrangement shown in FIG. 1; and,
FIG. 5 is a bottom view of the gemstone arrangement shown in FIG. 2.
The broken line showing of parts of the drawings is included for the purpose of illustrating use and environment and forms no part of the claimed design.