Special equipment: Candy thermometer
Place the water, sugar, and corn syrup in a 2-quart heavy-bottomed saucepan over medium-high heat. The corn syrup will make the cooked sugar harder and crunchier; it will also help prevent the cooked sugar from melting as quickly when it reacts to the humidity in the air. Insert a candy thermometer and cook the sugar mixture to 311 degrees F (155 degrees C), what is known as the hard crack stage. Stir the sugar slowly as it cooks to ensure that it cooks evenly. If you do not stir it, the mixture will develop hot spots and the sugar will cook faster in those spots. Use a pastry brush to keep the inside of the saucepan clean as the sugar cooks, or the sugar may recrystallize. To do this, dip a clean brush in cold water and brush the inside of the pan clean.
Remove the cooked sugar from the heat and pour it into a medium-size heatproof glass bowl. The glass bowl will hold the temperature and stop the cooking process. It will also allow you to reheat the sugar in the microwave if necessary. If you leave he sugar in the saucepan, the sugar will continue to cook and turn dark brown. Occasionally stir the hot sugar to keep it from darkening due to the residual heat. Stirring also helps to keep its temperature even. I put a towel under the bowl to keep it from tipping and to protect my hands from the heat of the glass.
Peel, core or pit, and halve the fruit as necessary. Use a sharp knife to slice the fruit into small pieces. (This is not necessary for berries or grapes.) Arrange the fruit on toothpicks or small skewers in any combination you like. Leave enough room at one end of the toothpick or skewer so you will be able to hold it as you dip it in the hot sugar. Dip each toothpick in the hot sugar, coating the fruits completely. Wipe the toothpick against the rim of the bowl to remove any excess sugar and place on a sheet of parchment paper. Repeat until all of the fruit has been dipped. The fruit skewers should release easily from the parchment paper as soon as they cool. You can arrange them on a plate or use your imagination to make a fruit skewer centerpiece.
If you use refrigerated fruit, allow it to come to room temperature a few hours before dipping it in the hot caramel. If you use cold fruit, condensation will form, creating moisture that will cause the sugar to melt. It is best to make these within three hours of the time you plan to serve them. Since fruit is mostly water, its moisture will cause the sugar to melt, which makes the treats sticky and gooey. When working with caramel, be sure to have a bowl of cold water on hand. If you get hot sugar on your fingers, immediately dip them in cold water to remove it and avoid a burn. To cool a hot thermometer, stand it upright in a tall container. Do not put in cold water, or it will break. Keeping it upright ensures the mercury will not separate as it cools. I usually buy the thermometers that come in a metal casing or cage. Always hang your thermometer when it is time to store it.