Diamonds can be scary.  If you’re a guy looking to purchase an engagement ring, maybe all you know is that they cost a ton of money. The idea of shopping for one is particularly intimidating, as you’re spending thousands of dollars on a complete mystery.

It helps to learn some basic vocabulary:

The Four C’s

The Four C’s--cut, color, clarity, and carat--are the criteria by which diamonds are graded. The system was developed by the Gemological Institute of America (GIA) and adopted by the entire industry.

The Four C’s are based on a diamond's rarity: the rarer the C (not necessarily the "prettier") the more the C contributes to the diamond's price. The Four C’s are completely independent of each other. For example, a diamond can have high color but a low clarity, or high clarity but a low cut, etc. So unless you know all of the Four C's, it’s impossible to compare one diamond to another.

For much more on the Four C’s, click here.

The Most Important C 

Cut matters. In fact, the most important of the Four C’s is Cut.

Cut represents up to 50% of the price of a diamond. A fully cut diamond has 57 or 58 facets (cuts). Think of facets as mirrors. If the facets are positioned properly, light enters the diamond, bounces across the various facets, and eventually leaves the diamond and dazzles the viewer's eye. If a single facet is not positioned properly, light leaks out of the diamond, and it never reflects fire, sparkle, or brilliance, and never reaches its full optical potential. The GIA cut grades are poor, fair, good, very good, excellent. When you are shopping, make sure you look for a grading report (see below) that rates the diamond's cut. 

Grading Reports

Grading reports issued by an independent laboratory (or one with no vested interest in buying or selling diamonds) accurately describe the clarity, color, fluorescence, proportions, symmetry, and weight of a diamond.

They also provide a “plot” of the diamond—a diagram that marks all of the stone's unique, microscopic characteristics and flaws. This is the best tool to judge a diamond.

Labs that issue grading reports do not all use the same degree of rigor. There are definite differences and you need to look for specific labs. For more on grading reports, click here.

Gemologists

A gemologist specializes in gemology, which is the science, art and profession of identifying and evaluating gemstones. To be considered a gemologist, a person must receive a gemologist degree from a professional school or certification program.

A graduate gemologist, or G.G., is someone thoroughly trained by the Gemological Institute of America (GIA) in all diamond, gemstone and pearl types. The distinguished G.G. designation at the end of an individual's name is instantly recognized around the world as the mark of a senior professional in the jewelry industry.

When you are buying a diamond look for a store that has a trained gemologist on staff as a good sign. If possible, have an independent trained gemologist help evaluate the diamond's you are considering by accompanying you or studying the diamonds' grading reports (online). 

Beware: There are absolutely no requirements for someone to call himself or herself an "appraiser." Anyone can hang a sign in a jewelry store saying "appraiser" and not be held accountable to anyone. Look for appraisers that are also gemologists. 

The “Magic Number”

Typically, every diamond buyer wants a stone size that hits the "magic number" (a half carat, 1 carat, 1.5 carats, etc.). Naturally, a large premium is charged once you reach these benchmark sizes, and the price-per-carat begins to jump geometrically instead of linearly.

To save money, consumers can try to find diamonds that weigh just below these sizes, since an untrained eye can't detect size differences in a well-cut diamond when they're within 8 points. Diamonds that weigh just below these benchmark sizes, however, are usually the result of a bad cut that unintentionally failed to hit the benchmark size.

Finding a diamond that weighs just short of the "magic number" and is still cut well, therefore, usually represents a great deal.  And that’s the real trick…determining the the diamond has been “cut well.’ Again, you probably can’t tell with your naked eye. You need a diamond expert.

Fluorescence

Fluorescence is the ability of a gemstone to glow under ultraviolet light. The effect of fluorescence on a diamond's quality and price is misunderstood in the jewelry industry. Depending on a diamond's color and clarity, the strength and color of its fluorescence could enhance its appearance and value, or it could do the exact opposite. In other words, sometimes fluorescence is good, sometimes it's not. If you are comparing two diamonds don't forget to compare fluorescence apples-to-apples. 

These are just the basics. For much, much more on diamonds in general, click here for our Frequently Asked Questions.