I think the experience gained from jewelry making, or the resources required for it, might need to be tweaked - at least for levels 5-8.
The real limitation on jewelry making is the time spent gathering and refining the resources (copper and amethyst). Thus, I'd suggest that an important parameter is the amount of experience gained per resource. The big increase is resources (3+3 -> 5+5 amethyst/copper) is not matched by the experience gained by level 7. I don't know whether it is by level 8 as I haven't got there yet, but I not a big jump in number of resources again at level 9.
This balance did seem to work reasonably well for the weapon making, where making items at your level was the fastest way to level up in that profession. I think it would be good to aim for the same with all professions.

