CUT
Diamond cutting can be traced back to the mid 1300s when European and Indian gem cutters first began to cut and shape rough diamonds. Since that time, there have been many cutting methods identified and published.
Of the 4Cs, Gemologists believe that cut has the greatest influence on a diamond's beauty. Diamonds have a unique ability to effectively manipulate light. This unique quality can only be realized with an extremely high level of accuracy during the cutting and polishing process. Where nature dictates the uniqueness of color and clarity, humans affect the cut. While cutting diamond rough, cutters must not only consider the proportions of a diamond, but also the craftsmanship of overall symmetry and polish as well.
A diamond's brilliance comes from light entering the crown and reflecting from one facet to another and returning back out the crown. A diamond that is cut too shallow or too deep will not reflect light properly and the diamond will not be as brilliant as a diamond with an excellent cut.
Of the 4Cs, Gemologists believe that cut has the greatest influence on a diamond's beauty. Diamonds have a unique ability to effectively manipulate light. This unique quality can only be realized with an extremely high level of accuracy during the cutting and polishing process. Where nature dictates the uniqueness of color and clarity, humans affect the cut. While cutting diamond rough, cutters must not only consider the proportions of a diamond, but also the craftsmanship of overall symmetry and polish as well.
A diamond's brilliance comes from light entering the crown and reflecting from one facet to another and returning back out the crown. A diamond that is cut too shallow or too deep will not reflect light properly and the diamond will not be as brilliant as a diamond with an excellent cut.
COLOR
The scale ranges from D which is totally colorless to Z which is a pale yellow or brown color. Brown diamonds darker than K color are usually described using their letter grade, and a descriptive phrase, for example M Faint Brown. Diamonds with more depth of color than Z color fall into the fancy color diamond range.
Diamond color is graded by comparing a sample stone to a masterstone set of diamonds. Each masterstone is known to exhibit the very least amount of body color that a diamond in that color grade may exhibit. A trained diamond grader compares a diamond of unknown grade against the series of masterstones, assessing where in the range of color the diamond resides. This process occurs in a lighting box, fitted with daylight equivalent lamps, that are UV filtered. Accurate color grading can only be performed with diamond unset, as the comparison with masterstones is done with diamond placed on its table facet and pavilion side facing upwards. When color grading is done in the mounting, the grade is expressed as an estimated color grade and commonly as a range of color. Grading mounted diamonds involves holding the mounted diamonds table close to the table facet of the masterstone and visually comparing the diamond color under the same color conditions as unmounted diamond grading. The resulting grade is typically less accurate, and is therefore expressed as a range of color. While a grading laboratory will possess a complete set of masterstonesrepresenting every color grade, the independent grader working in a retail environment works with a smaller subset of masterstones that covers only the typical grade range of color they expect to encounter while grading. A common subset of masterstones would consist of five diamonds in two grade increments, such as an E, G, I, K, and M. The intermediate grades are assessed by the graders judgement.
Diamond color is graded by comparing a sample stone to a masterstone set of diamonds. Each masterstone is known to exhibit the very least amount of body color that a diamond in that color grade may exhibit. A trained diamond grader compares a diamond of unknown grade against the series of masterstones, assessing where in the range of color the diamond resides. This process occurs in a lighting box, fitted with daylight equivalent lamps, that are UV filtered. Accurate color grading can only be performed with diamond unset, as the comparison with masterstones is done with diamond placed on its table facet and pavilion side facing upwards. When color grading is done in the mounting, the grade is expressed as an estimated color grade and commonly as a range of color. Grading mounted diamonds involves holding the mounted diamonds table close to the table facet of the masterstone and visually comparing the diamond color under the same color conditions as unmounted diamond grading. The resulting grade is typically less accurate, and is therefore expressed as a range of color. While a grading laboratory will possess a complete set of masterstonesrepresenting every color grade, the independent grader working in a retail environment works with a smaller subset of masterstones that covers only the typical grade range of color they expect to encounter while grading. A common subset of masterstones would consist of five diamonds in two grade increments, such as an E, G, I, K, and M. The intermediate grades are assessed by the graders judgement.
CLARITY
Accurate clarity grading as with other grading steps must be done with the diamond "loose" (not set into any mounting). Inclusions are often difficult to see from the crown side of the diamond, and may be concealed by the setting.
[edit]SizeThe first clarity factor which is assessed is a clarity characteristic's size. Larger characteristics are typically more noticeable under magnification, thereby placing the diamond into a lower clarity grade.
[edit]NumberThe second clarity factor which is assessed is the number of clarity characteristics. Generally the more characteristics the lower the clarity grade. This assessment is made by judging how readily they can be seen, not by the actual number of characteristics.
]PositionThe third clarity factor which is assessed is the characteristic's position. When an inclusion is directly under the table of the diamond it is most visible. An inclusion under the table and positioned close to a pavilion facet will reflect multiple times around the stone, giving this type of inclusion the name "reflector". Reflectors are graded as if each reflection were an inclusion (although in plotting the diamond it is only plotted once). For this reason, reflectors have a greater impact on the clarity grade. Inclusions become less visible when they are positioned under the crown facets, or near the girdle of the stone. These inclusions may often be more easily seen from the pavilion side of the diamond than from crown side of the diamond.
Additionally, the position of large feathers, knots and included crystals positioned where they extend to the girdle or crown of the stone affect the clarity grade. Diamonds worn in jewelry typically will withstand breakage, however inclusions of this nature and in these positions can pose a risk for further extension of the break in the structure of the diamond. Inclusions that are judged to pose at least a moderate risk of breakage to the stone are graded in the Included category.
[edit]NatureThe fourth clarity factor which is assessed is a characteristic's nature. The characteristic's nature determines whether it is internal (extending into the stone) or external (limited to the surface of the stone). Internal characteristics automatically exclude the diamond from the Flawless, and Internally Flawless categories. External characteristics exclude the diamond from the Flawless category.
An internal characteristic of a diamond may be classified as a(n): bruise, cavity, chip, cleavage, cloud, crystal, feather, grain center, indented natural, internal graining, knot, laser drill hole, needle, pinpoint, or twinning wisp.[1]
An external characteristic of a diamond may be classified as a(n): abrasion, natural, nick, pit, polish lines, polish mark, scratch, surface graining, or extra facet.
The nature will also determine whether an inclusion poses a risk to the stone. An inclusion that may cause a break in the crystal structure (included crystal, feather, knot, and cleavage) may, depending on its position, pose a moderate level of risk for further breakage.
[edit]Color or reliefThe fifth clarity factor which is assessed is the color and relief of clarity characteristics. Characteristics that contrast with the surrounding diamond are said to have "relief". The degree to which this color and relief is noticeable affects the clarity grade of the diamond. Colored inclusions invariably show contrast and are more easily seen. An exception is a black pinpoint inclusion which is often more difficult to see than a white pinpoint
[edit]SizeThe first clarity factor which is assessed is a clarity characteristic's size. Larger characteristics are typically more noticeable under magnification, thereby placing the diamond into a lower clarity grade.
[edit]NumberThe second clarity factor which is assessed is the number of clarity characteristics. Generally the more characteristics the lower the clarity grade. This assessment is made by judging how readily they can be seen, not by the actual number of characteristics.
]PositionThe third clarity factor which is assessed is the characteristic's position. When an inclusion is directly under the table of the diamond it is most visible. An inclusion under the table and positioned close to a pavilion facet will reflect multiple times around the stone, giving this type of inclusion the name "reflector". Reflectors are graded as if each reflection were an inclusion (although in plotting the diamond it is only plotted once). For this reason, reflectors have a greater impact on the clarity grade. Inclusions become less visible when they are positioned under the crown facets, or near the girdle of the stone. These inclusions may often be more easily seen from the pavilion side of the diamond than from crown side of the diamond.
Additionally, the position of large feathers, knots and included crystals positioned where they extend to the girdle or crown of the stone affect the clarity grade. Diamonds worn in jewelry typically will withstand breakage, however inclusions of this nature and in these positions can pose a risk for further extension of the break in the structure of the diamond. Inclusions that are judged to pose at least a moderate risk of breakage to the stone are graded in the Included category.
[edit]NatureThe fourth clarity factor which is assessed is a characteristic's nature. The characteristic's nature determines whether it is internal (extending into the stone) or external (limited to the surface of the stone). Internal characteristics automatically exclude the diamond from the Flawless, and Internally Flawless categories. External characteristics exclude the diamond from the Flawless category.
An internal characteristic of a diamond may be classified as a(n): bruise, cavity, chip, cleavage, cloud, crystal, feather, grain center, indented natural, internal graining, knot, laser drill hole, needle, pinpoint, or twinning wisp.[1]
An external characteristic of a diamond may be classified as a(n): abrasion, natural, nick, pit, polish lines, polish mark, scratch, surface graining, or extra facet.
The nature will also determine whether an inclusion poses a risk to the stone. An inclusion that may cause a break in the crystal structure (included crystal, feather, knot, and cleavage) may, depending on its position, pose a moderate level of risk for further breakage.
[edit]Color or reliefThe fifth clarity factor which is assessed is the color and relief of clarity characteristics. Characteristics that contrast with the surrounding diamond are said to have "relief". The degree to which this color and relief is noticeable affects the clarity grade of the diamond. Colored inclusions invariably show contrast and are more easily seen. An exception is a black pinpoint inclusion which is often more difficult to see than a white pinpoint
CARAT
Carat is the term used to describe the weight of any gemstone, including diamonds. Although the definition of a carat has changed over time, since 1913 the international standard has been 200 milligrams, or 1/5 of a gram. Often, jewelers describe carats in 1/4 increments.
In jewelry pieces with more than one diamond, the carats may be described in terms of total carat weight (TW). This is the combined total weight of all the stones in the piece.
Diamonds can range in size from a fraction of a carat to several carats. Given the rarity of large stones, however, the price increases rapidly with size; therefore, a single 2-carat diamond will cost much more than two 1-carat diamonds. Very large diamonds with good color and clarity are very rare.
Expect to pay a premium for stones that are above a full carat weight. For example, a .95 carat diamond will cost a bit more than a .90 carat stone.
Because round brilliant cuts follow exact standards, you can make a good estimate of the carat weight of the stone based on the stone's diameter. The following chart compares the relative sizes of stones and describes how much a round brilliant diamond of a certain size is likely to weigh. This chart is for educational purposes and represents a guideline for diameter and carat weights. It is not representative of other cuts or shapes. It is also not applicable to colored gemstones which have a different density from diamonds.
DIAMOND CARAT WEIGHT.03 carat.05 carat.07 carat.10 carat2.0mm diameter2.5mm diameter2.7mm diameter3.0mm diameter.15 carat.20 carat.25 carat.33 carat3.4mm diameter3.8mm diameter4.1mm diameter4.4mm diameter.40 carat.50 carat.65 carat.75 carat4.8mm diameter5.2mm diameter5.6mm diameter5.9mm diameter.85 carat1.00 carat1.25 carats1.50 carats6.2mm diameter6.5mm diameter7.0mm diameter7.4mm diameter1.75 carats2.00 carats2.25 carats2.50 carats7.8mm diameter8.2mm diameter8.6mm diameter9.0mm diameter
In jewelry pieces with more than one diamond, the carats may be described in terms of total carat weight (TW). This is the combined total weight of all the stones in the piece.
Diamonds can range in size from a fraction of a carat to several carats. Given the rarity of large stones, however, the price increases rapidly with size; therefore, a single 2-carat diamond will cost much more than two 1-carat diamonds. Very large diamonds with good color and clarity are very rare.
Expect to pay a premium for stones that are above a full carat weight. For example, a .95 carat diamond will cost a bit more than a .90 carat stone.
Because round brilliant cuts follow exact standards, you can make a good estimate of the carat weight of the stone based on the stone's diameter. The following chart compares the relative sizes of stones and describes how much a round brilliant diamond of a certain size is likely to weigh. This chart is for educational purposes and represents a guideline for diameter and carat weights. It is not representative of other cuts or shapes. It is also not applicable to colored gemstones which have a different density from diamonds.
DIAMOND CARAT WEIGHT.03 carat.05 carat.07 carat.10 carat2.0mm diameter2.5mm diameter2.7mm diameter3.0mm diameter.15 carat.20 carat.25 carat.33 carat3.4mm diameter3.8mm diameter4.1mm diameter4.4mm diameter.40 carat.50 carat.65 carat.75 carat4.8mm diameter5.2mm diameter5.6mm diameter5.9mm diameter.85 carat1.00 carat1.25 carats1.50 carats6.2mm diameter6.5mm diameter7.0mm diameter7.4mm diameter1.75 carats2.00 carats2.25 carats2.50 carats7.8mm diameter8.2mm diameter8.6mm diameter9.0mm diameter