Diamond Concentrates Watermelon THC Distillate. Can be used for re-fill for Diamond Concentrates Vape Pen. This Diamond Concentrates Watermelon distillate contains 1 gram of naturally flavored, distilled THC. This is some of the purest distillate you can get your hands on, so don’t hesitate to give it a try. This 91% THC product is supplied in a syringe for easy dabbing.