Mix scallops in a bowl with salt, pepper, olive oil, thyme, rosemary, garlic, pepper flakes and lemon juice. Blend well. Refrigerate 1 hour.
Meanwhile, cook orange juice over high heat until it is reduced by half. Add butter, tomatoes and coriander and cook briefly until well blended. Season with salt and pepper. Keep warm. Heat griller or grill until very hot. Place scallops on skewers. Brush with marinade, cook 4 minutes on each side. Serve immediately with orange-butter sauce.