In a large saucepan, add sugar, vinegar, salt, pickling spice, mustard seeds and turmeric. Stir to combine then bring to a rolling boil. Turn heat to simmer, cover and cook for 10 minutes. Remove pan from heat and let cool completely. Wash and slice cucumbers crosswise into 1/2 inch rounds for chips or lengthwise for spears. Place chips or spears and sliced onion into one 6-cup mason jar or two 3-cup mason jars. (Make sure jars are clean but not necessary to sterilize.) Pour cooled pickling marinade over pickles. Firmly pack pickles into the jar allowing 1/2 inch of pickling juice at the top. Seal jars and refrigerator for 48 hours. After opening, they will last 3 months.