In shallow glass dish, combine chicken pieces with lemon juice, coriander, cumin, salt, oregano, pepper and olive oil. Stir well, cover with plastic and allow to marinate in refrigerator for 1 hour, or up to overnight.
In medium bowl, combine yogurt, lemon zest, lemon juice, cumin, mint, salt and pepper. Cover and place in refrigerator until ready to serve.
Prepare gas or charcoal grill or preheat broiler.
Thread 5 chicken pieces and 5 red grapes, alternating, on a 12-inch wooden or metal skewer, or a sturdy rosemary branch. (If using wooden skewers, soak in water for one hour.) Place on grill and cook, turning, until done throughout, about 15 minutes.