Combine scallops and next 4 ingredients in a medium bowl; cover and chill 30 minutes.
Pick leaves off 6 inches of one end of each rosemary sprig, leaving the other end intact. Soak rosemary sprigs in water in a shallow dish 20 minutes.
Place 2 rosemary skewers side by side, leaving a small space between. Thread 3 scallops onto bare part of rosemary skewers. Repeat with remaining rosemary and scallops. Grill over medium-high heat 2 to 3 minutes on each side. Serve on a bed of basmati rice with lemon slices, if desired.
Note: For smoky flavor, cut slices of prosciutto in half lengthwise and wrap 1 piece around each scallop before skewering.
Wine note: "Soave Classico by Masi ($9) from Italy would do well here. The rosemary highlights floral notes in the wine, while (if using the prosciutto recipe variation) the prosciutto's saltiness and mild gamey flavors are softened. Often served with seafood, Soave is not overbearing, but food-friendly."--Franklin Ferguson, wine director and bar manager, Citrine restaurant, Los Angeles, CA.