Line an 8-inch square pan with foil and spray foil with cooking spray; set aside.
In a small bowl, sprinkle unflavored gelatin over 1/3 cup water; set aside.
In a small saucepan, combine 2 cups sugar and remaining water. Bring to a boil over medium heat. Cook and stir until the sugar dissolves. Cook, without stirring, until candy thermometer reads 260° (hard-ball stage). Remove from the heat.
Stir lemon gelatin and unflavored gelatin mixture into hot syrup; stir until sugar dissolves. Stir in lemon juice and zest. Pour into prepared pan. Cover and refrigerate overnight or until candy is set.
Combine edible glitter and remaining sugar; spread half of mixture over a 14x12-in. piece of paper. Invert candy onto the parchment. Cut candy into 48 triangles and coat with remaining glitter mixture. Store candy in an airtight container at room temperature for up to 1 week.
We recommend that you test your candy thermometer before each use by bringing water to a boil; the thermometer should read 212°. Adjust your recipe temperature up or down based on your test.