To make the margaritas juice the limes into a blender. Add the raspberries and the simple syrup. Blend until smooth.

Pour the mixture into a fine mesh strainer over top of a measuring cup or bowl.  Press to get all the juice out of the mixture then discard the solids.

Measure out ¾ cup of the mixture.   Reserve the rest for later.

Pour the sanding sugar into a shallow dish.

Rim two short glasses or margaritas glasses with a lime wedge. Dip the rim into the sanding sugar to give the glass a sugared rim.

Fill each glass with ice.   Add 1 ½ ounces of tequila to each glass.

Pour half of the raspberry margarita mixture into each glass.  Serve immediately.