I was hired as an onboard jeweller with Princess and I love it. We get a decent amount of port time and working in the jewellery shop is definitely a bit easier than the other shops.
I was hired by www.pmcmarine.com
They were great to deal with and took care of everything. Make sure you apply for a jeweller position if you have that experience. The $$ is better than a regular shoppie.
Hope this helps.