I am a master jeweler and I would like to find a decent marketplace to sell my goods.
If you have experience in this, please let me know. I even thought about opening my own store but the rent is too high.
What do you think about an online marketplace?

Everything is largely determined by how you intend to sell your products. If you want to run a profitable business, you must sell your created products on a regular basis and use the proceeds to fund new projects. I am confident that people will want to purchase your product, but it is critical that you find the right seller. You could also do the sale yourself, but then you’d have less time to create. Look for stores that could use your product to plans launch marketplace. Almost every company in the United States is on this list. You can approach one of the stores and discuss the possibility of selling.

Assuming you mean your own ecommerce store vs a platform, then yes, Wordpress with WooCommerce or any of those types of platforms can get you up and running. Happens every day for cheap.