I was referring to your query re: freshadamas looking too good to be true. I'm pretty small so 7-8 mm is an everyday size for me. For someone taller even 8-9 mm would not be too much for daily wear. Does this make more sense?
Ordering them from different stores would not be a good idea unless you want to send strands for matching. Matching does matter. I would not buy high grade pearls separately unless I brought the pearls in to be matched or if I were prepared to send them in by mail. 7-8 mm earrings with a 8-9 mm strand sounds great. In general I'd say for every millimeter increase in size the price nearly doubles. In theory the quality shouldn't really change because it's in the same grade, but at the same time in larger sizes the pearls are rarer, and it's harder to find pearls with the same surface quality. For esthetics, the larger pearls will look very mildly less lustrous and for the same percentage of surface blemishing allowed larger pearls look less flawless. 8-9 mm are pretty good as far as I can see though. The Jan gem necklaces were fantastic from what I heard. I didn't get it as I was looking for a graduated strand.