One of my favorite things to do in Paris is go to the flea market. There is just no better place in Paris to shop for real vintage clothing and jewelry. There are so many markets that would take me weeks to go to all of them.
They are only open on Saturdays and Sundays. If you’re lucky, some will be open for a half day on Monday. If you can take a cab there, do it. It will save you the headache of getting lost. Keep in mind that a lot of the antique shops and shops that carry vintage clothing and vintage jewelry are situated on the inside of the streets rather than facing the big roads.
One of my favorite shops to search for vintage jewelry is called Au Grenier De Lucie. The owner Heidi is so lovely and will work with you on the prices. She is located at Vernaison market, alle 1 stand 25.