When it comes to determining a diamond's quality and value, there is a universally accepted standard known as the Four C's: Cut, Color, Clarity, and Carat weight.

Cut

The cut of a diamond determines its ultimate beauty. A diamond cut to correct proportions will give off an unrivaled radiance. Cut a diamond too shallow or too deep, and light will escape through the bottom or sides.

Hearts and Arrows Diamonds

A perfectly proportioned ideal cut that is cut to the exacting specifications of a Tolkowsky Cut, Eppeler Cut or Scandinavian Standard will display a "Hearts and Arrows" pattern when observed through a IdealScope.

Diamond Shape

Round

This is the most classic shape. It is a 58 facet cut and gives maximum fire and brilliance. This shape has set the standard for all other diamond shapes.

Asscher

The Asscher cut is a squard cut characterized by a smaller table and larger step facet than and emerald cut. It features dramatic, cut corners. It usually has a high crown and deeper pavillion than todays emerald cut.

Pear

A hybrid cut, the pear combines the best of the oval and the marquise. It is shaped like a sparkling tear drop. It also belongs to the category of diamonds whose designes most compliment a hand with small or average length fingers. It is particularly beautiful for pendants or earrings.

Heart

The ultimate symbol of romance, heart, is a pear with a cleft at the top. The skill of the cutter determins the beauty of the cut. Look for a stone with an even shape and well defined outline.

Marquise

An elongated shape with pointed ends inspired by the fetching smile of the Marquise de Pompadour and commissioned by the sun king, France's Louise XIV, who wanted a diamond to match it.  It is gorgeouse when used as a solitaire or when enhanced by smaller diamonds.

Oval

An oval is a perfectly symmetrical design popular among women with small hands or short fingers. Its elongated shape gives a flattering illusion of length to the hand.

Princess

This is a square or emerald cut with numerous sparkling facets. It is a relatively new cut and often finds its way into solitaire engagement rings. Flattering to a hand with long fingers, it is often embellished with triangular stones at its sides. Because of its designe, this cut requires more weight to be directed toward the diamond's depth in order to maximize brilliance.

Trillian

First developed in Amsterdam, the exact designe can vary depending on a particular diamonds natural characteristics and the cutters personal preference. It may be a traditional triangular shape with pointed corners or a more rounded triangular shape with 25 facets on the crown, 19 facets on the pavilion, and a polished girdle. It is definitely for the adventurous

Emerald

A rectangular shape with cut corners. It is known as a step cut because its concentric broad, flat planes resemble stair steps. Since inclusions and inferior color are more pronounced in this particular cut, take pains to select a stone of superior clarity and color.

Radiant

A square or rectangular cut that combines the elegance of the emerald shape with the brilliance of the round. Its 70 facets maximize the effect of its color refraction. This cut requires more weight to be directed toward the diamond’s depth in order to maximize brilliance because of its design. Depth percentages of 70% to 78% are not uncommon.

Color

Diamonds occur in every color of the spectrum. While yellows, browns and grays are the most commonly found colors, the most desirable color is Colorless. Truly colorless gems are extremely rare.

Clarity

Clarity refersto the number of imperfections in the diamond, known as inclusions. The majority of diamonds have some degree of inclusions in them. The fewer inclusions, the more rare and valuable it is.

GIA Grading System

The following figure explains the GIA grading system for inclusions and imperfections. Considerations in grading the clarity of a diamond include the type of stone, point size and the location of inclusions. Inclusions that are near to, or break the surface, may weaken the diamond structurally, therfore reducing its value significantly. On the other hand, it may be possible to hide certain inclusions behind the setting of the diamond (depending on where the inclusion is located), thus minimizing any negative impact of the inclusion.

Diamond Clarity Designations

FL - "Flawless" no inclusions at 10 x magnification

IF - "Internally Flawless" no inclusions at 10 x mag. - Small Blemishes

VVS-1 -"Very Very Small" inclusions hard to see at 10 x Magnification

VVS-2 -"Very Very Small" inclusions. VVS1 better than VVS2

VS-1 -"Very Small" inclusions visible at 10 x mag. - not naked eye

VS-2 - "Very Small" inclusions VS1 is better grade than VS2

SI-1 - "Small" or "Slight" inlcusions or "Imperfections" may be "eye clean"

SI-2 - "Small" or "Slight" inclusions or "Imperfections" visible to naked eye

SI-3 - Inclusions large and obvious, little or no brilliance

I1 to I3 - Imperfect, with large Inclusions, fractures and flaws

Internal Diamond Inclusions

Carbon - Tiny black spots caused by undigested carbon inclusions (natts).

Clouds - Grouping of tiny pinpoints that may not resolve at 10X magnification, appearing cloudy.

Feathers - Cleavage planes or internal fractures that have the appearance of feathers.

Grain Center - Concentrated area of crystal growth that appear light or dark.

Internal Graining- Irregular crystal growth resulting in internal distorions, waviness, or a haze.

Needles - Rutile-like needle shaped inclusions.

Pinpoints - Minute crystals within the diamond that appear white.

Twinning Wisps - Inclusions resulting from crystal twining during growth.

External Diamond Inclusions

Bearded Girdles - Fine cracks, chips, fringing, or feathers along the outer edge of the girdle.

Bruising - A percussion mark caused by impact.

Cavities - An indentation resulting from a feather or damage during polishing.

Chips - Damage usually occuring on the sharp edge of a facet.

Knots - An inclusion that penetrates the surface, appearing as a raised area.

Indented Naturals - A natural indentation that was not removed by polishing.

Filled Fractures - Fractures that have been artificially filled.

Pits - Dislodged pinpoint inclusions at the surface.

Surface Grain Lines - Visible surface lines caused by irregular crystallization during formation.

Fracture Filling

Diamond clarity is sometimes enhanced by filling fractures, much like repairing a crack in your car's windshield. Such diamonds are sometimes called "fracture filled diamons". According to FTC guidelines, vendors should disclose this enhancement, and reputable filling companies will use filling agents which show an orange or pink flash of color.

Thers is a significant price discount for fracture-filled diamonds. The GIA will not grade fracture-filled diamonds, in part because the treatment isn't permanent. Reputable companies often provide for repeat treatments if heat causes damage to the filling. The heat generated by a blowtorch used to work on settings can cause damage, therfor it is essential to inform anyone working on a setthing if the diamond is fracture-filled, so they use greater care while working on the piece.

Human Caused Surface Blemishes

Abrasions - whitish haziness along the junction of facets caused by wear.

Nicks - Small chips at facet junctions.

Scratches - Grinding wheel marks of scratches from contact with other diamonds.

Burn marks - Surface burning from heat buildup during polishing.

Carat

Diamonds are sold by weight in carats. Each carat is 1/5 of a gram. The heavier the diamond, the more valuable it is. But bigger doesn't necessarily mean better. Quality is found in diamonds of all sizes.

What size diamond should you buy? Well, that weighs heavily on your budget. A general guideline for a diamond engagement ring is to spend two month’s salary but it’s not a rule so don’t feel that you have to abide by it. Deciding on a carat size means striking a balance between size and quality. If she prefers larger jewelry pieces, you can still buy her a large diamond by staying within your budget. Just choose one that is graded lower in color and clarity. Remember, that slender fingers made diamonds look bigger. If she has small fingers, a 1 carat diamond will look proportionately large and a larger stone may appear too big. The setting you choose should be made to fit the carat weight of the diamond.