Terms Describing Features, Cuts or Properties of a Diamond
Abrasion - Tiny nicks along facet junctions, producing white fuzzy lines instead of sharp crisp facet edges.
Bezel - A facet on the Crown, or upper part of the Diamond above the Girdle.
Blemish - A clarity characteristic that occurs on the surface of a diamond, which is an imperfection external to the diamond.
Bow Tie Effect - An effect caused by a shadowy area visible in some fancy shapes, caused by light leaking out the bottom of the Diamond.
Brilliance - The brightness that seems to come from the very heart of a diamond. It is the effect that makes diamonds unique among all other gemstones. While other gemstones also display brilliance, none have the power to equal the extent of diamond's light-reflecting power.
Bruise - An inclusion consisting of surface crumbling, often accompanied by tiny, root like feathers.
Cavity - An inclusion consisting of a large or deep opening in the diamond.
Chip - A tiny piece missing, caused by normal wear and tear, or by cutting.
Cloud - A group of tiny white inclusions that result in a milky or cloudy appearance.
Culet - The smallest facet at the bottom of the diamond.
Emerald Cut - A step cut, usually rectangular.
Excellent Cut - A GIA and HRD-CGL grade for excellent cut and polish of brilliants.
Extra Facet - A facet placed without regard for symmetry and not required by the cutting style.
Facet - Plane, polished surface of a diamond.
Eye-Clean - A term used in the jewelry industry to describe a diamond with no blemishes or inclusions that are visible to the naked eye.
Faceted Girdle - Sometimes cutters polish the girdle into 32 facets.
Feather - A separation or break due to either cleavage or fracture, often white and feathery in appearance.
Flaw - An imperfection of a diamond.
Fluorescence – The mostly blueish glow of a diamond in high ultraviolet lighting conditions. Ratings: none, faint, slight, medium, strong blue. Strong blue fluorescence may cause the diamond to appear oily in daylight.
Fracture - A crack on the diamond's surface.
Grain Center - A small area of concentrated crystal structure distortion, usually associated with pinpoints.
Hue - Pure, spectral (prismatic) color. Hues include gradations and mixtures of red, organdy, yellow, green, blue, violet and purple.
Included Crystal - A mineral crystal contained in a diamond.
Inclusion - Imperfection internal to the Diamond.
Internal Graining - Internal indications of irregular crystal growth. May appear milky, like faint lines or streaks, or may be colored or reflective.
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. While these are blemishes, they might also be regarded as a sign of skilled cutting; the presence of a natural reflects the cutter's ability to design a beautiful polished gem, while still retaining as much of the original crystal's weight as possible. In many cases, naturals do not affect the clarity grade. In most cases, they are undetectable to the naked eye.
Needle - A long, thin included crystal that looks like a tiny rod.
Oval Cut - A type of fancy shape diamond, which is essentially an elongated version of a round cut.
Pear Cut - A type of fancy shape diamond that resembles a teardrop.
Pinpoints - Miniscule spots internal to a diamond. A cluster of pinpoints can form a cloud.
Pit - A tiny opening, often looking like a white dot.
Point - 100th of a carat.
Polish Lines - Tiny parallel lines left by polishing. Fine parallel ridges confined to a single facet, caused by crystal structure irregularities, or tiny parallel polished grooves produced by irregularities in the scrape surface.
Polish Mark - Surface clouding caused by excessive heat (also called burn mark, or burned facet), or uneven polished surface resulting from structural irregularities.
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.
Surface Graining - Surface indication of structural irregularity. May resemble faint facet junction lines, or cause a grooved or wavy surface, often cross facet junctions.
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 an indicator of the quality of as diamond's cut; it is graded as Ideal, Excellent, Very Good, Good, Fair or Poor.
Trilliant Cut - A type of brilliant fancy shape that is triangular.
Areas and Parts of a Diamond
Crown - The upper part of the diamond above the girdle. Consists of a large flat area on top called a table, and several facets below it.
Crown Angle - The angle at which a diamond's bezel facets (or, on emerald cuts, the row of concentric 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. White light entering at the different angles in broken up into its spectral hues, creating a beautiful play of color inside the diamond. The crown angle also helps to enhance the brilliance of a diamond.
Depth - The height of a diamond from the culet to the table. The depth is measured in millimeters.
Depth Percentage - There are two different measurements of a diamond's depth- the actual depth in millimeters and the depth percentage, which expresses how deep the diamond is in comparison to how wide it is.
Girdle - The outer edge or the widest part of the diamond forming a band around the diamond.
Pavilion - The bottom part of the Diamond, below the girdle.
Table - The flat facet on the top of the diamond. It is the largest facet on a cut diamond.
Table Percentage - The value that represents how the diameter of the table facet compares to the diameter of the entire diamond.
Miscellaneous Diamond Terms
AGS - American Gem Society. An educational institution for gemological studies. The AGS Labs were created primarily to develop and promote universally accepted standards for grading cut.
Carat Weight - The metric carat, which equals 2 milligram, is the standard unit of weight for diamonds and most other gems. If other factors are equal, the more a diamond weighs, the more valuable it will be.
Clarity - A diamond's relative position on a flawless to imperfect scale. Clarity characteristics are classified as inclusions (internal) or blemishes (external). The size, number, position, nature, and color or relief of characteristics determines the clarity grade. Very few diamonds are flawless, that means, show no inclusions or blemishes when examined by a skilled grader under 10X magnification. If other factors are equal, flawless diamonds are most valuable.
Color - Grading color in the normal range involves deciding how closely a diamond's body color approaches colorlessness. Most diamonds have at least a trace of yellow or brown body color. With the exception of some natural fancy colors, such as blue, pink, purple, or red, the colorless grade is the most valuable.
Cut - The proportions and finish of a polished diamond (also called make). Cut can also mean shape, as in emerald cut or marquise cut. Proportions are the size and angle relationships between the facets and different parts of the diamond. Finish includes polish and details of facet shape and placement. Cut affects both the weight yield from rough and the optical efficiency of the polished diamond; the more successful the cutter is in balancing these considerations, the more valuable the diamond will be.
Certificate - Laminated document by a gemological institute to describe a Diamond's characteristics.
Diamond - A crystal made up of 99.95% pure carbon atoms arranged in an isometric, or cubic, crystal arrangement. It is this unique arrangement of the carbon atoms that makes diamond look and behave differently from other pure carbon minerals such as graphite.
Fancy Diamond - A diamond with an attractive natural body color other than light yellow or light brown.
GIA - Gemological Institute of America. This institute provides reliable diamond certification.
Loupe - Magnifying glass usually of 10X.
Zirconium - Zr is a natural occurring metal. Synthesized in crystal form, also called cubic zirconium
Wednesday, April 16, 2008
Diamond Clarity Grading
The least important diamond grade is clarity. Unfortunately, it is what many jewelers claim is most important, because it is the easiest to demonstrate. Anyone can put a diamond under a microscope and see if it has inclusions. It takes gemological knowledge to cut and/or color grade a diamond. Jewelry merchants with little or no formal gemology training often resort to a quick demonstration of clarity, which has made it the most important grade to many consumers. This could not be further from the truth.
By definition, any grade diamond of SI2 and above requires magnification to see the inclusion. How often do your friends look at your diamond under a loupe? Since any diamond of SI2 clarity and up is considered "eye clean," meaning you must have magnification to see any inclusion, why worry about clarity above the SI2 range? Of course, if you are told you are getting a VS1 you want make sure you actually are. But you can save lots of money by buying a diamond that is well proportioned, with good color, but is in the SI1 or SI2 clarity range. To put it another way, a perfectly cut diamond of D color and SI2 clarity will look the same to everyone around you as a perfectly cut diamond of D color VS1. However, the SI2 diamond could save you thousands of dollars.
The I1 to I3 graded diamonds are the primary diamond grades you should consider. Many jewelry stores only promote the clarity and color grades, in that order. This is not the proper approach. Diamond values are set more on cut and proportion than on clarity and color. Cut and proportion determine a diamond's value and should be considered first when buying a diamond. Leave clarity for last. It’s the one area where you can save a lot without giving up beauty.
By definition, any grade diamond of SI2 and above requires magnification to see the inclusion. How often do your friends look at your diamond under a loupe? Since any diamond of SI2 clarity and up is considered "eye clean," meaning you must have magnification to see any inclusion, why worry about clarity above the SI2 range? Of course, if you are told you are getting a VS1 you want make sure you actually are. But you can save lots of money by buying a diamond that is well proportioned, with good color, but is in the SI1 or SI2 clarity range. To put it another way, a perfectly cut diamond of D color and SI2 clarity will look the same to everyone around you as a perfectly cut diamond of D color VS1. However, the SI2 diamond could save you thousands of dollars.
The I1 to I3 graded diamonds are the primary diamond grades you should consider. Many jewelry stores only promote the clarity and color grades, in that order. This is not the proper approach. Diamond values are set more on cut and proportion than on clarity and color. Cut and proportion determine a diamond's value and should be considered first when buying a diamond. Leave clarity for last. It’s the one area where you can save a lot without giving up beauty.
Ideal Diamond Cut - (Part 2)
Diamond proportioning began in 1919 when a mathematician named Tolkowsky used numerical formulas to achieve the modern brilliant cut. He did this by cutting a diamond so that all light entering the stone followed a controlled path to exit the top of the diamond.
In 1919 the diamond cutting industry was not advanced enough to apply Tolkowky’s mathematical angles and dimensions. Instead it used variations of the cut, based on what the technology of the time could do. As technology advanced, so did the ability to better approximate the ideal Tolkowsky cut, which provides the best return of light in a diamond. It is possible for an experienced diamond grader to estimate, within a decade, when an older diamond was cut by observing where on the technology timeline its proportioning falls and how well is achieves Tolkowsky's ideal cut formula.
The best cut casts a perfect shadow on a wall when a beam of light is shone on it. Very few will do that because, due to many factors, most diamonds deviate from the perfect cut. The perfect cut diamond is difficult to achieve, and many people differ as to what is a perfectly cut diamond.
A properly cut diamond is proportioned so that no matter where light enters the stone...from the top, sides or bottom… the light is directed out the top of the stone. This is difficult to achieve, but mathematically possible. The reason is that a diamond is cut to capture light entering it from a 360-degree sphere.
Controlled Path of Light
In a properly cut diamond, all light entering, no matter from what direction or angle, will always exit out the top of the stone. This is what makes a diamond sparkle.
“Flash for the Cash” is crucial in diamond evaluation and diamond buying. Cut and proportioning can account for a 20 to 40 percent difference in price between diamonds that are otherwise equal. In other words:
Store A may offer you a SI1/H 1.00ct diamond for $6,500.00.Story B may offer you a SI1/H 1.00ct diamond for $5.000.00.
You may think that Store B is giving you a significant discount directly from the wholesaler or the diamond mines, but what they don’t tell you is that you are getting a shallow or deep cut diamond and not an ideal cut. Remember, when you shop for diamonds there is more to diamond grading/pricing than just clarity and color. There is also the cut grade.
In 1919 the diamond cutting industry was not advanced enough to apply Tolkowky’s mathematical angles and dimensions. Instead it used variations of the cut, based on what the technology of the time could do. As technology advanced, so did the ability to better approximate the ideal Tolkowsky cut, which provides the best return of light in a diamond. It is possible for an experienced diamond grader to estimate, within a decade, when an older diamond was cut by observing where on the technology timeline its proportioning falls and how well is achieves Tolkowsky's ideal cut formula.
The best cut casts a perfect shadow on a wall when a beam of light is shone on it. Very few will do that because, due to many factors, most diamonds deviate from the perfect cut. The perfect cut diamond is difficult to achieve, and many people differ as to what is a perfectly cut diamond.
A properly cut diamond is proportioned so that no matter where light enters the stone...from the top, sides or bottom… the light is directed out the top of the stone. This is difficult to achieve, but mathematically possible. The reason is that a diamond is cut to capture light entering it from a 360-degree sphere.
Controlled Path of Light
In a properly cut diamond, all light entering, no matter from what direction or angle, will always exit out the top of the stone. This is what makes a diamond sparkle.
“Flash for the Cash” is crucial in diamond evaluation and diamond buying. Cut and proportioning can account for a 20 to 40 percent difference in price between diamonds that are otherwise equal. In other words:
Store A may offer you a SI1/H 1.00ct diamond for $6,500.00.Story B may offer you a SI1/H 1.00ct diamond for $5.000.00.
You may think that Store B is giving you a significant discount directly from the wholesaler or the diamond mines, but what they don’t tell you is that you are getting a shallow or deep cut diamond and not an ideal cut. Remember, when you shop for diamonds there is more to diamond grading/pricing than just clarity and color. There is also the cut grade.
Diamond Cut Introduction
What makes one diamond sparkle while another looks lifeless and dull? A good diamond is dazzling, romantic and priced according to quality. The most important factor is the grading and evaluation of a diamond’s cut. The purpose of this lesson is to provide a basic understanding of the evaluation of cut and proportioning and how it impacts a diamond’s beauty and value.
Parts of a Diamond
Parts of a diamond are named by the various facets. It is important for any jewelry industry professional to learn the parts of the diamond to be able to properly communicate with consumers and dealers regarding diamond evaluation. Let's take a look at the facets and parts. The numbers beside the facet indicate how many of each facet is in one modern, brilliant cut diamond. This number may vary with different cutting styles, but for our purposes the modern brilliant is the mainstay of our study.
Parts of a Diamond
Parts of a diamond are named by the various facets. It is important for any jewelry industry professional to learn the parts of the diamond to be able to properly communicate with consumers and dealers regarding diamond evaluation. Let's take a look at the facets and parts. The numbers beside the facet indicate how many of each facet is in one modern, brilliant cut diamond. This number may vary with different cutting styles, but for our purposes the modern brilliant is the mainstay of our study.
Diamond Tutorial - Online Diamond Education
We have organized our lessons into three categories. You may have seen other places list the 4 C's or the 5 C's (Cut, Clarity, Carat, Color, and Cost). We only have three lessons (Cut, Clarity and Color) because all features influence cost and carat size is not relevant to how well a diamond is made.
Our intention is that you learn about diamonds and become educated in the diamond buying process. With proper education, buying a diamond is not complicated. These lessons are designed to guide you in purchasing a diamond successfully.
Our intention is that you learn about diamonds and become educated in the diamond buying process. With proper education, buying a diamond is not complicated. These lessons are designed to guide you in purchasing a diamond successfully.
Thursday, December 20, 2007
What is the Difference Between a Certification and an Appraisal?
A certification is a survey of your gem that defines or grades certain features or qualities with internationally recognized values. These features are often known by the 4C acronym. An appraisal is a valuation or market price based on this specification.
What Guarantee Does a Certification Give Me?
There are numerous laboratories for certification. Two of the main ones are the Gemological Institute of America (GIA) and the European Gemological Institute. Here at Diamond Doctor we use the GIA exclusively, because that is the Gold Standard in the industry. Yes, they are more conservative. Often by quite a large margin, and that’s because they are a totally independent, non-profit laboratory staffed by 900 of the world’s leading diamond graders, scientists and educators, all with a mission to “ensure the public trust in gems and jewelry.”
The GIA is the creator of the famous 4C’s of diamond value (color, clarity, cut and carat weight) and the birthplace of the International Diamond Grading System, now used as the industry standard. The GIA have graded all of the world’s renowned stones including: The Hope Diamond (45.52 carats), the Taylor-Burton Diamond (69.42), the Alnatt (101.29 carats), the De Beers Millennium Star (203.85 carats), the Centenary Diamond (273.85 carats) and the Incomparable Diamond (407.78 carats)
The GIA is also where the White House and the Congress go for definitive answers. It is where the textbooks on diamonds are written.
The EGL on the other hand is partly funded by the European jewelry industry and in our opinion, is not as professional, reliable or accurate as the GIA. Even though the EGL consistently gives higher grades for the same stones and would therefore make our sales price seem more attractive, we are more interested in providing you the equivalent of a Supreme Court ruling on your purchase.
A certification is a virtual specification.
The GIA is the creator of the famous 4C’s of diamond value (color, clarity, cut and carat weight) and the birthplace of the International Diamond Grading System, now used as the industry standard. The GIA have graded all of the world’s renowned stones including: The Hope Diamond (45.52 carats), the Taylor-Burton Diamond (69.42), the Alnatt (101.29 carats), the De Beers Millennium Star (203.85 carats), the Centenary Diamond (273.85 carats) and the Incomparable Diamond (407.78 carats)
The GIA is also where the White House and the Congress go for definitive answers. It is where the textbooks on diamonds are written.
The EGL on the other hand is partly funded by the European jewelry industry and in our opinion, is not as professional, reliable or accurate as the GIA. Even though the EGL consistently gives higher grades for the same stones and would therefore make our sales price seem more attractive, we are more interested in providing you the equivalent of a Supreme Court ruling on your purchase.
A certification is a virtual specification.
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