When you're planning to ask someone to marry you, you want everything to be perfect. And one of the biggest parts of that is the ring you place on their finger. But since most people are not gem experts, it can be overwhelming to try to figure out how to find the perfect stone for the perfect setting that expresses how you feel.

If you're feeling this dilemma, here is a quick guide to diamond buying. 

Start With a Shape

Diamonds come in a variety of cuts, sizes, and shapes. Knowing the basics about the shape and size you want will help you navigate the rest of the process. Look at the rings or other jewelry your soon-to-be fiance already owns. If you see a pattern to the shapes, you will have an idea what to look for. If you still can't decide, it's usually safe to go with a classic round or princess (square) cut.

Figure Out a Budget

How much money you're planning to spend is the next thing you'll want to know. The quality and size of diamonds will vary greatly based on your budget, so there's no point in shopping outside your price range. It may make the process more stressful and less fun than it should be. 

Learn the Four Cs

The so-called "Four Cs" of diamonds are clarity, color, cut, and carats. Start with the best diamond in these categories that's a little over your price range. Why? You can then reduce the quality of each "c" until you're within your budget but haven't sacrificed all the luxury you began with.

You can reduce your diamond price by opting for a slightly lower clarity, since this may be a category many people won't notice too much. Clarity is basically the level of imperfections in a gemstone--both inside and on the surface. A diamond rated VS2, for example, has only very small inclusions within the diamond structure. 

If you still haven't reached your price point without sacrificing noticeable clarity, you can choose a diamond that has a slightly different color. A perfect diamond is nearly colorless, but the color differences in gems with slight yellowing are often not noticeable to an untrained eye.

The final category to reduce price is the carat weight of the stone. This may be the category most easily noticed by the wearer, so save this sacrifice until you've reached the limits of the other choices.

Knowing how to make the right choices--both for you and for your wallet--will help ensure that you choose the best possible diamond to light up the face of that person you want to spend the rest of your life with.