Casting jewelry is a mystery

Thus far I have fabricated everything I have made but have often
wondered how to go about getting a few pieces cast. I decided to
strike out on my own (as is my nature) and ordered the Delft clay
casting system. The thing that always stumps me is how to allow for
shrinkage so that stones can be fit. I do not do my own lapidary or
faceting. I have read one article in the archives about something
making tools to enlarge a setting, but I didn’t follow it well.

If there is a pretty simple approach to how one can go about casting
a piece that will then accommodate a particular stone, I’d
appreciate hearing it.

Thanks
J. S. Ellington
jsellington.com