Like a fingerprint, each diamond is unique and each has different qualities that influence its beauty and value. Because there are so many characteristics used to explain the quality of a diamond, shopping for a diamond engagement ring can feel overwhelming but it doesn't have to be.
The 4C's refers to the four criteria used for diamond grading and certification – Carat, Color, Clarity, and Cut. The 4C's was developed by the GIA in response to a desire to have a universal grading system for objectively comparing and evaluating the quality of diamonds.
Carats are the standard unit of weight for diamonds and other gemstones. A carat is divided into 100 points, similar to how a dollar is divided into 100 pennies. Therefore, a 50-point diamond weighs 0.50 carats
- One metric carat is equal to 0.2 grams.
- A diamond's carat weight may not always be an accurate indication of its size. For example, some diamond shapes, may appear larger than others but actually have a lower carat weight. That is, a marquise-cut diamond may often appear larger than a round-cut diamond even though the round diamond has a heavier carat weight.
- Additionally, diamonds of equal weight can have very different measurements and therefore, be different in size.
- Diamond weight alone is also not a determining factor of value. The value of a diamond also depends on the other members for the 4C's.
The color of a diamond refers to the amount of color, or lack of color, in a diamond.
- Many factors influence the overall look of a diamond's color including: body color, shape, size, proportions, and the position and lighting in which it is viewed.
- Color in a diamond generally manifests itself as a pale yellow.
- The GIA developed color grading standard in the 1950's and it is now regarded as the industry standard.
- The color scale runs from D-Z. The scale begins with the letter D – the highest possible color grade, which indicates a complete lack of color, to the letter Z – the lowest possible color grade, which indicates noticeable color in distinct shades of yellow or brown.
- D – F: Colorless. No discernible color in present.
- G – H: Near Colorless. Color will be difficult to detect, unless compared to a diamond with a higher color grade.
- I – J: Near Colorless. Presence of a slightly detectable warmth or undertone.
- K – Z: Noticeable Color.
- Some diamonds emit a visible light known as fluorescence, or photo-luminescence, when exposed to invisible ultraviolet (UV) radiation. Fluorescence is caused by trace amounts of the element Boron found in a diamond and fluorescence is neither good nor bad. In many cases, it makes the diamond more beautiful. Various colors of fluorescence in diamonds occur; however, blue is by far the most common.
Clarity refers to the tiny, natural imperfections that occur in almost all diamonds.
- These imperfections go by a variety of names including inclusions and blemishes.
- A diamond's clarity grade is determined using the GIA International Diamond Grading System. The system uses a scale, which contains 11 grades ranging from FL-IF to I3.
- FL (Flawless): No inclusions or blemishes are visible to a skilled grader using 10X magnification. Very rare.
- IF (Internally Flawless): No inclusions and only blemishes are visible to a skilled grader using 10X magnification. Very rare.
- VVS1 and VVS2 (Very, Very Slightly Included): Inclusions are difficult for a skilled grader to see under 10X magnification.
- VS1 and VS2 (Very Slightly Included): Inclusions are clearly visible under 10X magnification but can be characterized as minor.
- SI1 and SI2 (Slightly Included): Inclusions are noticeable to a skilled grader using 10X magnification.
- I1, I2, and I3 (Included): Inclusions are obvious under 10X magnification and may affect the transparency and brilliance of a diamond.
The cut of a diamond determines its brilliance and it has the greatest overall influence on a diamond's beauty and value. For these reasons, cut is a diamonds must important characteristic.
- The Cut Scale ranges from: Excellent, Very Good, Good, Fair, and Poor.
- When learning about diamond cut it is helpful to begin with the shape of a diamond. Diamond shapes include:
- Round, Princess, Emerald, Asscher, Marquise, Oval, Radiant, Pear, Heart, Cushion
Shape describes a diamond's form. Each diamond shape has unique attributes, which distinguish it from other diamond shapes. Ultimately, choosing a diamond shape is a matter of personal preference.
- Round – The round-cut diamond is the most popular diamond shape. Round diamonds traditionally have 57 or 58 facets. The round shape typically allows for more flexibility in terms of balancing cut, color, and clarity grades while still getting the desired fire and brilliance.
- Princess – Princess-cut diamonds are characterized by their square shape, pointed corners, and brilliant-cut facets. The shape can vary in how square or rectangular they are.
- Emerald – Emerald-cut diamonds are distinguished by their differently shaped pavilion, which is cut with rectangular or step-cut facets. These facets are parallel to one another, as opposed to brilliant-cut facets, which have opposing facets that mirror one another. The cut creates a larger table, which highlights the clarity and can make any natural imperfections more visible. As with princess-cut diamonds, the shape of an emerald-cut diamond can vary in how rectangular they are.
- Asscher – Asscher-cut diamonds are closely related to the emerald-cut diamonds, except that they are square. Asschers have the same rectangular facets, which create a unique optical appearance, as well as, highlight the clarity. As with emerald-cut diamonds, the facets highlight the diamond's clarity and may make natural imperfections more visible.
- Marquise – Marquise-cut diamonds have brilliant facets. The shape of a marquise diamond can also maximize carat weight, giving the impression of a larger-looking diamond.
- Oval – Oval-cut diamonds have brilliant facets similar to round diamonds. Ovals can vary in their length to width ratio, with some oval-cut diamonds being shorter and wider and others being longer and thinner.
- Radiant – Radiant-cut diamonds are characterized by trimmed corners, a square shape, and brilliant facets. Radiant-cut diamonds can vary in their degree to rectangularity.
- Pear – Also called a teardrop, for its single point and rounded edges, the pear has brilliant-cut facets and can vary in terms of its length to width ratio.
- Heart – The heart-cut diamond is uniquely shaped with brilliant-cut facets.
- Cushion – Also known as a "pillow-cut" diamond. The cushion-cut diamond is characterized by rounded corners and larger facets, which increase the diamond's brilliance. The larger facets also highlight the diamond's clarity, which can make natural imperfections more visible. Cushion-cut diamonds also range in shape from square to oval or rectangular.
A diamond certificate is a report created by an expert gemologist or gemological institute, which provides an analysis of a diamond's dimensions, clarity, color, polish, symmetry, and other characteristics. The most well known and respected gemological institute is the GIA, the Gemological Institute of America.
During the certification process, a diamond is evaluated, measured and scrutinized by a trained individual using a jeweler's loupe, a microscope, and other industry tools.
A complete diamond certificate typically includes the following information:
- A report number
- Date the report was created
- Shape and Cutting style of the diamond
- The measurement of the diamond
- Carat weight
- Color grade
- Clarity grade
- Finish, including polish and symmetry.
Most reports will also include two reference diagrams. One depicts the front and back of the diamond, indicating the presence and location of any imperfections, as well as, a legend describing those symbols. The second diagram depicts the proportions of the diamond.