Faceting Design Tables

People often ask about appropriate sizes for gem designs – or whether a given design could or should be cut in a rough of a given size. There are a number of different ways to answer those questions, but getting it down to a formula could be a little complicated. I settled on a formula based on the average percentage of the sphere occupied by the average facet.

This table shows the relationship between gemstone size and facet count for RI = 1.54

Remember, these are broad and general guidelines, not absolute rules.

Site supporters can access tables for RI = 1.45, 1.54, 1.6, 1.7, 1.8, and 2.1

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