Prepare an 8" x 8" pan by lining it with parchment paper. Use enough paper to go up to the sides of the pan. Sprinkle some coconut on the parchment paper and set aside until needed.
Measure and place your ingredients within easy reach. Add sugar, cornstarch, gelatin, and cream of tartar in a medium-sized pot. Whisk to combine.
Mix cold water and lemon juice in a large cup or bowl. Pour the liquid over the contents of the pot. Whisk quickly, to prevent clumping, until smooth.
Continue to whisk, over low heat, until very thick. This should take approximately 30 minutes. Meanwhile, heat a pan on another burner and toast the shelled pistachios over low heat for a few minutes.
After approximately 20 minutes of cooking, whisk the pomegranate juice and rose water into the pot. (If you prefer a deeper color add some red food coloring). If the mixture is too thick, you can use a spoon or a spatula to mix it. Stir continuously to prevent the bottom of the mixture from sticking to the pot.
The Turkish delight will start to bubble and eventually pull away from the bottom of the pot. When this happens, stir nuts into the mixture and turn out into the prepared pan.
Smooth the top of the Turkish delight with a spatula and sprinkle with coconut. Allow to set on the counter for approximately 8 hours or overnight.
Remove the Turkish delight from the pan by lifting the parchment paper out of the pan and flipping it onto a cutting board. Dust the cutting board with coconut and cut the Turkish delight into cubes using a sharp knife or a dough scraper. Toss cubed Turkish delight with the remaining coconut to keep the pieces from sticking together. Store in an airtight container.