There may be nothing sweeter than giving jewelry on Mother’s Day, but those feelings can be tarnished if it turns out you got a bad deal. That can be especially true if you are paying a lot of money. And this Mother's Day, that's more likely to be the case than in previous years. According to the National Retail Federation's annual survey, Americans plan to spend $5 billion on jewelry this Mother's Day. That's up from $4.2 billion last year. The first thing to do when buying jewelry is to make sure you are educated about the kind of jewelry you are interested in, says NerdWallet retail and shopping expert Courtney Jespersen. Cost can depend on issues such as individual craftsmanship, but comparing prices at different retailers can help you gain a sense of what a certain diamond cut might fetch, for instance. Jespersen also recommends that novice jewelry buyers bring along a friend or relative who has more expertise for advice. Then, think about the financial a...