The first place to check would be The Jewelers Circular Keystone at
They do a yearly census for the Jewelry Industry. I am not sure
they will cover the exact target you are looking to cover but it is
you will most likely find useful.
To do a very specific research report for the you are
looking to cover, you may want to contact a university in your area.
Get in touch with a professors that teaches Business and Marketing.
They may be willing to do a class project that is specific to what
you want. If not they may be willing to have some of the students
contact. You might be able to hire the students to do the research
at a far lower cost than a Market Research company.
Custom Jewelry - Handmade Jewelry - Antique Jewelry