You’ve shopped, you’ve surfed, you’ve read, you’ve consulted with family and friends. You have a good idea how cut, color, clarity and carat size affect the quality and price of a diamond. So what do you do? How do you decide which diamond is the perfect expression of your sentiments – and your beloved’s expectations?

Style seeking
Start by determining the shape of diamond you plan to buy. Brilliant round or a fancy cut? If the two of you have been shopping together (or you are getting not-so-subtle hints) you'll have this narrowed down. But if you're planning a surprise, you’ll need to do some homework.

Try to remember: any interest in a particular shape of diamond in a window – or on one of her friends? That’s a big clue. You can also ask one of her close friends or a relative for advice – if you can swear them to secrecy.

Otherwise, you’ll have to rely on your powers of observation and your instincts. What is their style when it comes to clothing? If taste tends to be classic styles in traditional cuts, you probably can't go wrong with a timeless brilliant round diamond in a prong “Tiffany” setting. If they are more of an adventurous dresser, seeking out designer styles or more of an individualist, it might be time to think beyond tried and true. Consider a fancy-cut stone, or a center stone accented with other gemstones.