Begin by washing your green or red grapes thoroughly under cool water. Dry them completely using a clean kitchen towel or paper towels.

In a medium saucepan, combine granulated sugar, water, and light corn syrup. Heat over medium heat, stirring occasionally until the sugar dissolves. Bring to a rolling boil for 2-3 minutes.

Divide the candy syrup into three bowls. Add white gel food coloring to one, pink to another, and blue to the last. Mix until vibrant for a marbled effect.

Using a fork, dip a grape into one of the colored syrups. Allow excess to drip off, then swirl it in contrasting colors for a marbled look.

Place the coated grapes on parchment paper, spaced apart. Allow to set at room temperature for about 30 minutes.

Once hardened, enjoy immediately or store in an airtight container for up to two days.