I am helping my sister buy diamond cluster earrings. The design is generally a center round diamond and six similarly sized round diamonds around the center. I noticed that some clusters have central prong set diamonds while others have the center diamond without prongs and tucked under the outer ring of diamonds. I suppose the latter gives a more continuous look to the earring, but I think the use of prongs on all stones keeps them secure, shows them all off and keeps them level with each other. Anyone with detailed knowledge of cluster mountings have an opinion on this?