Diamond Quality & The 4Cs
Learning about diamonds begins with an understanding of the basic characteristics, often referred to as The Four Cs. These are standards by which diamonds are graded, compared, and ultimately valued.
Understanding the ways diamonds differ from one another will help you understand the tradeoffs of the Four Cs against another important factor – price.
Diamond Color – Each diamond is graded using a scale created by one of the leading gemological industry organizations. An ideal stone is colorless, however most stones posses some form of color.
Diamond Carat – The Carat is the measure of the actual weight of the diamond. A carat is divided into 100 points. A 0.50 carat diamond may also be referred to as 50 points.
The greater the weight of the diamond, the more rare it is.
Carat weight is not always the same as size appearance.
The choice of how a diamond is cut is a critically important factor in determining whether a diamond looks its weight.
Stones that have too high a depth percentage carry more weight in the height of the diamond where it does not add to the visual size appearance.
Diamond Clarity – The clarity of a diamond refers to the presence of internal inclusions occurring naturally within the crystal structure.
Almost all diamonds have some degree of inclusions, but in higher quality of diamonds, inclusions are not visible to the naked eye.
The higher the clarity of a diamond, the more rare it is.
Diamond Cut – Cut refers to the angles and proportions of the diamond and determines how brilliant, beautiful and valuable the diamond is.
Cut is the only aspect of a diamond determined by the skill and artistry of the craftsman’s hand.
A finely cut diamond will have exquisite brilliance and beauty while maximizing size appearance.
Achieving the best cut is not about extra facets, special viewing devices or other gimmicks. It’s about using expertise to unlock the maximum brilliance from within the diamond.
Brilliance: The brightness that appears to come from the heart of a diamond. With a level that is unique to diamonds, other gemstones posses lesser levels and don’t have the ability to equal the extent of diamond’s light-reflecting power. Brilliance is produced primarily when light makes its way into the table, reaches the pavilion facets, and is then reflected back out through the table, where the light is most visible to your eye.
Brilliant Cut: One of three variations of faceting layouts. In this type of arrangement, all facets appear to radiate out from the center of the diamond toward its external edges. It’s called a brilliant cut because it is designed to maximize brilliance. There are a number of brilliant cuts like round diamonds, ovals, radiants, princesses and more.
Carat: The unit of weight by which a diamond is measured. One carat equals 200 milligrams, or 0.2 grams originating from the use of carob beans to measure the weight of gemstones.
Carbon Spots: This term refers to imperfections called included crystals that have a dark appearance, rather than a white or transparent appearance, when viewed under a microscope.
Cleavage: The propensity of crystalline minerals, such as diamond, to split in one or more directions either along or parallel to certain planes, when struck by a blow. Cleavage is one of the two methods used by diamond cutters to split rough diamond crystals in preparation for the cutting process (sawing is the other method).
Clouds: A grouping of a number of tiny inclusions that is too small to be distinguishable from one another, even under magnification. Not visible by the naked eye, they look like a soft, transparent cloud under a microscope.
Color Grading: A system of grading diamond color based on their colorlessness (for white diamonds) or their spectral hue, depth of color and purity of color (for fancy color diamonds).
Crown: The upper portion of a cut gemstone, which lies above the girdle. The crown consists of a table facet surrounded by either star and bezel facets (on round diamonds and most fancy cuts) or concentric rows of facets reaching from the table to the girdle (on emerald cuts and other step cuts).
Crown angle: The angle at which a diamond’s bezel facets intersect the girdle plane. This gentle slope of the facets that surround the table is what helps to create the dispersion, or fire, in a diamond.
Culet: A very small flat facet that diamond cutters commonly add at the base of a diamond’s pavilion. Its purpose is to protect the tip of the pavilion from being chipped or damaged.
Cut: This refers both to the proportions and finish of a polished diamond. As one of “the Four Cs” of diamond value, it is the only man-made contribution to a diamond’s beauty and value.
Depth: The height of a diamond from the culet to the table.
Depth Percentage: On a diamond grading report, you will see two different measurements of the diamond’s depth-the actual depth in millimeters (under “measurements” at the top of the report) and the depth percentage, which expresses how deep the diamond is in comparison to how wide it is. This depth percentage of a diamond is important to its brilliance and value; where that depth lies can be equally important.
Diamond Cutting: The method by which a rough diamond that has been mined from the earth and shaped into a finished, faceted stone.
Diamond Gauge: An instrument used to measure a diamond’s length, width and depth in millimeters.
Dispersion: Also known as “fire” it the manner in which the light is broken and reflected. Components of light are broken into spectral colors (for example, red, blue and green and appears as a play of small flashes of color across the surface of the diamond as it is tilted.
Emerald Cut: A square or rectangular-shaped diamond with cut corners.
Eye-Clean: A jewelry industry term to describe a diamond with no blemishes or inclusions that are visible to the naked eye.
Facet: The smooth, flat faces on the surface of a diamond. They allow light to both enter a diamond and reflect off its surface at different angles, creating the wonderful play of color and light for which diamonds are famous.
Fancy Shape: Any diamond shape other than round.
Feathers: These are small fractures in a diamond.
Finish: This term refers to the qualities imparted to a diamond by the skill of the diamond cutter. The term “finish” covers every aspect of a diamond’s appearance that is not a result of the diamond’s inherent nature when it comes out of the ground.
Fluorescence: An effect that is seen in some gem-quality diamonds when they are exposed to long-wave ultraviolet light.
Girdle: The outer edge, or outline, of the diamond’s shape.
Heart-shape Cut: A type of fancy diamond cut, which is cut to resemble the popular Valentine’s Day shape.
Inclusion: A clarity characteristic found within a diamond. Most inclusions were created when the gem first formed in the earth.
Laser-Drill Holes: One of the few man-made inclusions that can occur inside a diamond. An intentionally created inclusion can actually raise its clarity grade.
Length-to-Width Ratio: A comparison of how much longer a diamond is than it is wide. It is used to analyze the outline of fancy shapes only; it is never applied to round diamonds.
Marquise Cut: A type of fancy shape diamond which is elongated with points at each end.
Naturals: Small parts of the original rough diamond’s surface which are left on the polished diamond, frequently on or near the girdle.
Oval Cut: A type of fancy shape diamond which is essentially an elongated version of a round cut.
Pavé: A style of jewelry setting in which numerous small diamonds are mounted close together to create a glistening diamond crust that covers the whole piece of jewelry and obscures the metal under it.
Pavilion: The lower portion of the diamond, below the girdle.
Pear Cut: A type of fancy shape diamond that resembles a teardrop.
Point: A unit of measurement used to describe the weight of diamonds. One point is equivalent to one-hundredth of a carat.
Polish: Refers to any blemishes on the surface of the diamond which are not significant enough to affect the clarity grade of the diamond.
Princess Cut: A type of brilliant cut fancy shape that can be either square or rectangular.
Radiant Cut: A type of brilliant cut fancy shape that resembles a square or rectangle with the corners cut off.
Ratio: A comparison of how much longer a diamond is than it is wide.
Semi-Mount: A jewelry setting that has the side stones already mounted, but which contains an empty set of prongs which are intended to mount a diamond center stone that the customer selects separately.
Single-Cut: A very small round diamond with only 16 or 17 facets, instead of the normal 57 or 58 facets of a full cut round brilliant.
Step Cut: One of three styles of faceting arrangements.
Symmetry: Refers to variations in a diamond’s symmetry. The small variations can include misalignment of facets or facets that fail to point correctly to the girdle (this misalignment is completely undetectable to the naked eye). Symmetry is regarded as a quality indicator of a diamond’s cut; it is graded as Ideal, Excellent, Very Good, Good, Fair or Poor.
Table: The flat facet on the top of the diamond. It is the largest facet on a cut diamond.
Table percentage: The value which represents how the diameter of the table facet compares to the diameter of the entire diamond.
Trilliant Cut: A type of brilliant fancy shape that is triangular.