I'll have to go home and measure them.
UPDATE: I don't have calipers, so I'm trying to eyeball it with a ruler.
The Kojima strand (shorter, paler strand) is 13 mm for the center pearl, and only slightly smaller for the others.
The Pacific Pearls strand (longer strand) is 15 mm for the center pearl with 12 mm pearls next to it. But most pearls are in the 12-13 mm range.
They're all baroque, so it's a little hard to get a precise measurement. They're way bigger than I thought I would ever like. And then PSS set in.