I have a tourmaline of approximate size of 6.6mm (round), however there is a stock setting from a vendor that I really like, good price, but the largest they have them in is for a size 6.5 mm stone...do I dare order this semi mount (local jeweler will set my stone) will it even fit? or do I need to just go up and find a setting elsewhere for a 7mm round instead? I thought there would be some wiggle room?Thanks!