In a small bowl, mash half of the raspberries with the handle end of a wooden spoon, adding honey, if desired. Divide among 2 to 4 tall glasses or tumblers. Divide the remaining raspberries among the glasses. Divide the lime juice among the glasses, then fill each halfway with crushed ice. Top off with seltzer and garnish the rim of the glass with a thin slice of lime, if desired.