Diamond grading is subjective. The location of inclusions can mean that not all diamonds with the same grade are the same. The same quantity and size of inclusions on 2 diamonds with the same VS grade can look drastically different because of their location, and their orientation to the desired setting.

The 4 C’s of Diamond Buying according to the GIA: carat, cut, color and clarity.

Carat

A diamond’s size is measured in Carat Weight. Each diamond carat is also equal to 100 points. For example, a diamond that is a ½ carat can also be referred to as a 50 point diamond.

Cut

The cut of the diamond is also referred to as the shape. Shapes include Round Brilliant, Princess Cut, Emerald Cut, Marquise Cut, Oval Cut, Radiant Cut, Pear Shape, Heart shaped and Assher Cut. When a diamond is cut to good proportions, light is refracted from one facet to another, then dispersed through the top of the diamond. A well cut diamond - regardless of its shape - sparkles, has more fire, and offers the greatest brilliance. 

Color

Color is the natural body color visible in a diamond and is the one C determined completely by nature, not man. As a rule, the closer a diamond is to colorless, the more valuable and beautiful it is. Diamond colors appear in a range from D to Z. Color grades D, E and F are considered colorless, making them rare; grades G, H and I are near colorless; and grades J down are going to have a considerable amount of color. 

Clarity

Clarity is an indication of a diamond's purity. When a rough stone is extracted from carbon, deep beneath the earth, tiny traces of natural elements are almost always trapped inside. These elements are called inclusions, though sometimes they are referred to as birthmarks, because they are formed naturally and are unique to each stone. Clarity ranges from flawless (FL); internally flawless (IF); very, very slightly included (VVS1-VVS2); very slightly included (VS1-VS2); slightly included (SI1-SI3); and included (I1-I3).

Here's how to tell if you've picked the right jewelry store:

1.  They've got a big selection

Since you're going to put so much effort into finding a quality jewelry retailer, the last thing you want to have to do is search around every time you need another piece of jewelry!   Luckily, a good store will offer everything from engagement rings, to luxury watches, to designer earrings, to one-of-a-kind bracelets, and more.  No matter what you want to wear, they'll have it for you!

2.  They'll be happy to give you an explanation

All diamonds aren't created equally!  If you want to make the perfect purchase, you'll need to understand the cut, the color, AND the clarity.  That's why it's so important to find a jewelry store that will take the time to explain all of these things.  They'll also give you the "grade" for each of your potential diamonds so that you know you're getting the most bang for your buck.

3.  They'll have a good history

If your jewelry store has been around for years and years, you can rest easy knowing you've made a good decision!  After all, the less-than-stellar retailers don't survive very long.

4.  They'll have trained eyes

The jewelry appraisal you get is only as good as the expert who gives it to you!  If your appraiser doesn't have a trained eye, he may miss something important -- something that could cost you big-time down the road.

As an added benefit, those trained eyes will ensure that your jewelry store only has the very best pieces to choose from!

5.  They'll place a big emphasis on the details

After all, the details are what separate good jewelry from great jewelry!  A good retailer will help you create a custom piece, pick out the best materials, and even offer top-notch "other stuff" so that your jewelry is as strong, sturdy, and beautiful as possible.

6.  They'll have an ability to make your old jewelry look as good as new

No matter how careful you are, jewelry will always get dirty, and there's always a chance that something will eventually break.  (After all, these are teeny-tiny pieces we’re talking about!)  Luckily, a good jewelry store will handle all of its repairs on-site, so that you never have to worry about your stuff leaving your sight!