If you have already reached level 36 in the game, you may see the message "First talk to Eva" on the jewelry workshop and the message "First fix the jewelry workshop" on the pond with pearls in the buildings section of the store on your Home Island.
These captions indicate that there are some other quest lines, which ought to be finished, before you can unlock these new items.
To unlock the jewelry workshop, players should finish mysterious island missions, find the mysterious egg and upgrade the pyramid on home island. Only after that a new quest line about the jewelry workshop will begin.
To unlock the pearl pond, players should finish pearl island storyline.
Good luck in your adventures!