Start by thoroughly washing your grapes in cool water. Optionally soak in vinegar-water for about 5 minutes, then dry completely.

In a medium saucepan, combine white sugar, water, and light corn syrup. Stir gently, insert a candy thermometer, and place over medium-high heat to boil.

Continue boiling without stirring until the thermometer reads 300°F, indicating the hard crack stage. Remove from heat.

Carefully stir in the white gel food coloring and flavored oil. Mix in colored gel if using, until you achieve a consistent color.

Dip each skewer of grapes into the hot sugar mixture, allowing excess syrup to drip off. Optionally roll in colorful sprinkles.

Transfer to parchment paper or a silicone mat and let cool for about 15 minutes until candy coating hardens. Refrigerate for quicker setting.