In a small pot, combine the sugar and 1/2 cup water. Heat over medium-high heat until the mixture comes to a boil and the sugar dissolves. Remove from heat and allow to cool, approximately 10 minutes. You have just made your own simple syrup!
Meanwhile, slice your limes and muddle 2-3 raspberries in the bottom of each serving glass. (If you have an ice maker, gather about 4 cups of ice.
Add 2 Tablespoons lime juice, 2 Tablespoons simple syrup, and 3 Tablespoons gin to each glass, overtop of the raspberries. Top with 1 cup of ice and 1/2 cup of soda water.
Garnish as desired, with lime slices and additional raspberries.