Hi using the silver tube settings for the first time to make a ring and trying to figure out what size of faceted stone to use. Can anyone please help? For example what size of stone should I use for the NVW 846c setting - 4.6 mm external diameter and internal dia 3.8 mm and also for the next size ie 5.00 mm ext diameter and 4.2 internal diameter. I plan to order the stones from Cookson but need to know first. Thanks