Use a ring sizer and measure your finger; please trace it on a piece of paper and forward it to me. I will then email the sizes I have available in vintage thimbles that should give you a reasonable fit. I am happy to change these out for thirty days for another type; even a new one should you so desire. These thimbles are ones I have collected over the last few years. Some are very old, some not so old, and some only thirty years old. Many copies have been made, and some style are still available from the same company. Hence, I can make no guarantees on their age. I can assure you though, that it took a lot of polishing to get them clean for the pictures!
If you are a collector, or just beginning to collect, and want a recommendation, I would always suggest to buy ones with British Hallmarks on them. The hallmarks provide the assay office, the manufacturer, the year it was produced, and the maker’s mark. Four very useful pieces of information to ensure its authenticity. American made thimbles do not offer that sort of history. Even now, you can spot some that are new but made to look old.