The cut of a diamond has the most effect on its sparkle, or brilliance. Even if the diamond has perfect color and clarity, a poor cut can make a diamond look dull.

Determining a diamond's cut grade, however, goes beyond simple measurements of width and depth. Using an optical measuring device, a three-dimensional model is created to determine the diamond's proportions and angles. The interrelations between these various dimensions will greatly affect how light reacts once it enters and how it behaves once it exits; by using sophisticated computer modeling, it is possible to trace light behavior and measure its levels of brightness, fire and scintillation - the face-up appearance.

Diamonds with very little color are the most highly valued and are priced accordingly. A little color can diminish a diamond's brilliance. To help you choose the most brilliant diamond, Blue Nile offers diamonds with the highest grades of color.

Acting as a prism, a diamond can divide light into a spectrum of colors and reflect this light as colorful flashes called fire. Just as when looking through colored glass, color in a diamond will act as a filter, and will diminish the spectrum of color emitted. The less color in a diamond, the more colorful the fire, and the better the color grade.

The weight of a diamond is measured in carats. Since larger diamonds are more rare than smaller diamonds, diamond value tends to rise exponentially with carat weight.

Once you've determined what cut, color, and clarity grade you're looking for in a diamond, it's easy to determine the carat weight of diamond that will fit within your budget.

To choose the best carat weight of diamond, consider her style, the size of her finger, the size of your setting, and your budget.

If you have a set budget, explore all your options and you'll find that there is a wide range of diamond carat weights and qualities available in your price range.

If your recipient is very active or not used to wearing jewelry, she may find herself bumping or nicking her new ring. Consider a smaller size diamond or a setting that protects a larger diamond from getting knocked against doors and counters.

Also keep in mind that the smaller the finger, the larger the diamond will appear. A 1½-carat diamond solitaire looks much larger on a size 4 finger than a size 8.

If you have already chosen a setting, make sure you choose a diamond to fit. Look for the diamond size specifications of your ring or ask your Blue Nile diamond and jewelry consultant what size diamond you should look for.

Finally, if a large carat weight is important to you, yet you're working within a budget, consider a diamond with a good cut, SI1–SI2 clarity, and an I or J color grade.

But the best way to determine what size is best is by getting an idea of what she is expecting. If you plan carefully, you can get some answers without even raising her suspicions.

 

Diamonds with few flaws, or inclusions are very rare and highly valued. Clarity is graded based on the number, location, size, and type of the inclusions found in a diamond.

Diamonds that are absolutely clear are the most sought-after and therefore the most expensive. But many diamonds have inclusions — scratches, trace minerals or other tiny characteristics that can detract from the pure beauty of the diamond. The GIA and AGSL use a detailed system of rules and standards to summarize the number, location, size, and type of inclusions present in a diamond.

There are two types of flaws: inclusions and blemishes. Inclusions refer to internal flaws and blemishes refer to surface flaws. However, in the diamond grades listed below, you'll note that none of the grades include the term "blemish" -- for the purposes of grading diamonds, all flaws are called "inclusions."

For grades F through SI, a diamond's clarity grade impacts diamond's value,
not on the unmagnified diamond's appearance.

• F = Flawless: No internal or external flaws. Extremely rare.
• IF = Internally Flawless: no internal flaws, but some surface flaws. Very rare.
• VVS1-VVS2 = Very Very Slightly Included (two grades). Minute inclusions very difficult to detect under 10x magnification by a trained gemologist.
• VS1-VS2 = Very Slightly Included (two grades). Minute inclusions seen only with difficulty under 10x magnification.
• SI1-SI2 = Slightly Included (two grades). Minute inclusions more easily detected under 10x magnification.
• I1-I2-I3 = Included (three grades). Inclusions visible under 10x magnification and visible with the human eye. We do not recommend buying diamonds in any of these grades.

Which Clarity Grade Should I Choose?

Diamonds do not have to be flawless to be stunning.

Diamonds with VVS and VS grades are excellent choices for both value and appearance.

More affordable are those diamonds which gemologists call "eye-clean". Eye-clean are diamonds with no inclusions visible to the naked eye. SI1 and SI2 are eye-clean and unless the recipient carries a jewelry magnifying glass, the inclusions won't be visable.

With I1-I3 it may be possible to see the visible flaws without a magnifying glass. Not all "visible" flaws are "equally" visible so you really need to see this diamond before you buy to determine how visible/noticeable the flaws are. If you do choose to buy a I1-I3 diamond, remember that some people will look at it and immediately see the flaws.

 

The most important step in choosing a diamond is reviewing the diamond certificate, referred to by diamond grading labs as a grading report. A grading report documents the characteristics of a diamond, like the four Cs. Before purchasing a diamond, review a copy of its grading report, as this is proof that it has undergone an unbiased, professional examination.

A diamond certificate, also called a diamond grading report, diamond dossier®, or diamond quality document, is a report created by a team of gemologists. The diamond is evaluated, measured, and scrutinized using trained eyes, a jeweler’s loupe, a microscope, and other industry tools. A completed certificate includes an analysis of the diamond’s dimensions, clarity, color, polish, symmetry, and other characteristics. Many round diamonds will also include a cut grade on the report.

Many people think diamonds are indestructible, but they do require care. Diamonds are the hardest substance on earth. They are uniquely resistant to damage by heat or scratching, and can be cut or polished only by another diamond — but an extremely hard blow to the girdle can cause a diamond to chip. By having your diamond set in a relatively protective setting, and remaining conscious of it on your finger, you can keep your diamond intact for a lifetime. Exposure during ordinary wear to perspiration and household chemicals, like chlorine and hairspray, can cause buildup that dulls the surface of a diamond. We suggest periodic cleanings to keep the diamond brilliant and refractive.

A solution of one part ammonia and six parts water can be used to clean diamond jewelry at home. If cleaning by hand, gentle scrubbing with a soft brush should loosen most dirt and greatly increase the brilliance of the diamond, but be careful not to scratch the metal of your setting. Once a year, it is a good idea to have your diamond cleaned and have the security of the setting checked.

We recommend that all diamond jewelry is stored individually in soft cloth pouches when not being worn to prevent the diamond or diamonds from scratching or dulling other jewelry.