Drain cherries; place on paper towels to drain for 8 hours.
Line a baking sheet with aluminum foil; coat foil with cooking spray, and set aside.
Combine sugar, corn syrup, and water in a small heavy saucepan. Place over low heat, stirring until sugar dissolves. Bring to a boil over medium heat; cover and cook 2 to 3 minutes to wash down sugar crystals from sides of pan. Uncover and cook, without stirring, until a candy thermometer registers 325° (6 to 8 minutes).
Working quickly and holding cherry by the stem, dip each cherry into hot syrup to coat. Place cherries, stem up, on foil-lined baking sheet. Let cherries cool and harden.