I think the biggest consideration specific to jewelry is to select a partner who is known for high-quality work (if outsourcing your orders). The last thing you want is to do is deal with clients who are unhappy with poorly made jewelry. An experienced jewelry outfit is worth their weight in gold.
With outsourcing jewelry, in particular, it is important to have a dialogue with both your client and the company doing the job about the specific requirements of the order. Essentially, you will work as a liaison between both parties to ensure that the finished jewelry is exactly what the client has in mind including sizing, style, finish, engraving type, etc. It is also important to ensure that the companies you work with do high-quality work as their work reflects directly on your work. It never hurts to ask for a few referrals before beginning to work with new partners.
-Matthew Olian, Grateful Glass