In a large mason jar, add the peels from 1 grapefruit, 1/2 cup is sugar, and 1/2 cup water. Allow the peels to soak for 1 hour- not much longer or else they will get bitter. Remove the peels and refrigerate the syrup!
For the Paloma
In a mason jar, combine the tequila and grapefruit simple syrup, and lime juice. Add ice and shake well. Pour into a cocktail glass over ice, and add the seltzer as a float on top. Garnish with fresh lime and grapefruit.