Grease an 8-inch square casserole dish with the vegetable oil and set aside. In a small bowl, combine the pectin with 1/4 cup of the sugar and set aside.

Place the pineapple in a food processor and puree until very smooth. Transfer the pineapple puree to a 3-quart saucepan and add 1 3/4 cups of the sugar, the lime juice, and lime zest. Bring the contents of the pan to a boil over high heat, stirring with a spoon to dissolve the sugar. Once the fruit has come to a boil and the sugar is dissolved, reduce the heat to low and simmer for 2 minutes.

Sprinkle the pectin mixture over the pineapple mixture and whisk to blend. Raise the heat to medium-high and return the pan to a boil. Cook the candy, whisking constantly, until the liquid has evaporated, the consistency is very thick and syrupy, and the volume is reduced to 1 1/2 cups, about 15 to 20 minutes. Remove from the heat and pour into the prepared casserole dish. Place the casserole dish on a wire cooling rack and allow to cool completely. Let stand at least 12 hours, and up to 24 hours, until candy has firmed up.

Once the candy has firmed up, cut into 1-inch squares. Place the sanding sugar in a medium size bowl, and toss the candy cubes in the sugar to evenly coat. Serve immediately.