If your ex tries to take you to small claims to collect, he will be going to the wrong court. All the disputes between you have to be resolved through your divorce, and that would include any requirement that he return your jewelry.
In most cases, the person who gets to the courthouse first in a divorce will win, so apply to enforce your divorce terms to obtain the return of your jewelry. That will put him in the defensive position.
Hope this perspective helps & good luck!
If the debt occurred during marriage and it was a community debt, then the court still has jurisdiction and you may have to go back to the court to sort it out. He cannot do it in small claim court but the original family court. The court would want to know the reason the debt was omitted. If it was intentionally concealed then the settlement can be set aside within a certain time limits, according to family code 2122.
A weekly guide with tips and legal advice for each stage of the process.