Christmas and Valentine's Day are two of the top choices for giving diamond jewelry. There's a strong association with each for romance, and many people have high expectations for the gifts they are given at those times.

The challenge is picking just the right piece.

Many people love diamonds set in white gold. For the clearest, whitest diamonds this is the best choice, as it does not add color to the diamond. It allows the beauty to shine through, undiminished.

As you shop, consider what is in her jewelry wardrobe already, as well as the kinds of clothing she likes to wear. Some women prefer a very plain, elegant style, while others want their jewelry to make a statement with its styling.

Fortunately, this is not too hard to figure out. Just look at what she wears. If her earrings, rings and pendants are most often solitary stones or very simple designs, with plain gold around it, simple is probably best. If there tends to be a larger number of gemstones involved or the gold is highly detailed, you will probably want to look more at the style of the piece you buy.

There are many advantages to shopping early. This gives you the most time to think about what you would like to give as a gift, rather than picking from what is left over. While a narrowed selection is more comfortable for some people, there is something about knowing that you have chosen a perfect gift that is worth the extra effort.

Quality matters quite a bit. I've seen people buy what they are told are "milk diamonds", when in fact what they have is a very cloudy, flawed diamond. No sparkle or beauty at all. When possible, you should get at least a basic idea as to the quality of diamonds you are purchasing. For single stones this can be specific, with a fully rated stone, while multiple stones may be best described with a range.

You won't always be able to get this information because not all diamonds are rated. But you can pay attention to whether a company ranks the diamonds as A, AA, AAA or AAAA, knowing that the more "A"s the ring has, the better they consider the stones to be, and that the differences can be quite significant.

The quality of other materials matters as well. As a rule, if a diamond is set in 10K gold, it is probably lower quality. Higher karat gold tends to get better quality diamonds. Not always, but often enough for a decent rule of thumb. Similarly, platinum settings generally have better diamonds in them.

If there is one thing to be said about shopping online for diamonds, it is that the selection is really hard to beat. You have far more options shopping online than you ever would at your local jewelry store. There's also no worries about crowds, parking or store hours. You shop when you want.