The responsibility for shipping an item depends on the country and the situation. In Germany for example, a professional seller is responsible for the shipping. i.e. that the item is delivered to the customer. In contrast, a private seller is only responsible for the item until he has given it to the logistics partner. If the item is lost during shipping, he cannot be held responsible for that.
The insurance also seems to depend on the country. Again Germany as an example (I don't know the situation in NL): No courier insures jewelry or watches. Even if you buy an additional insurance from them (DHL offers such worthless insurances), watches are not covered. You need a special courier for valuables or a special insurance like secursus.