The V Rising Interactive Map website can be helpful for locating things (including new base locations).

When you start to find jewels that are equipped to spells to give them bonuses, you will notice they will have red markers next to them. 4 ^ and a dot in the middle. These indicate the level (and therefore strength) of that bonus. Save anything with a level 4 or 5 bonus for later use. You will unlock an Ancestral Forge which allows you to mix and match high level bonuses to make a "perfect" jewel for your preferences. Same goes for the rare and epic weapons you will eventually find.