We have built different websites, jewellery as well.
I can recommend you two must-have features for a jewellery website:
1) ability for customers to buy a set (for example chain + kulon or earings + necklace + a ring with the option to choose a ring size)
2) Image zoom functionality to view the details of the jewellery

Also a great contribution to any website is an ability to send auto emails to customers in order to get a review. A review form is included in an e-mail.