EDUCATION

terminology

vintage – over roughly 50 years old
estate – having a previous owner, sometimes with provenance
antique – hand-made and often with hallmarks of the maker
period – denotes certain age or time periods with unique / distinct styles, stones, metals, etc.

periods:

victorian
1837 – 1901
edwardian
1901 – 1915
arts & crafts
1890 – 1923
art nouveau & deco
1895 – 1935
retro
1935 – 1960

 

timeline

diamond education

4Cs of diamonds

The 4Cs – cut, color, carat weight, clarity – are used world-wide to classify the rarity of diamonds. Diamonds with the combination of the highest 4C ratings are more rare and, consequently, more expensive. Light is the element that ignites a diamond’s brilliance and fire. Its interplay with each of the 4Cs will help explain why one diamond can appear even more beautiful than another. The good news is that you don’t need to buy the rarest diamond to find one whose beauty speaks to you.

Cut

edu1The cutting of a diamond and its proportioning, called “Make” in the jewelry trade, are of extreme importance. The fire (variety and concentration of the prismatic colors emitted) and the brilliance (liveliness or sparkle, of the diamond) directly depend on the proper cutting and proportioning of the diamond. Cut refers not only to the shape of the diamond, but its proportions and finish, factors that influence the final cost of the diamond. Diamonds deliver the most intense flashes and variety of colors to the eye when properly cut of any of gemstones.

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edu4The following grading range will keep us in the proper range for a great diamond.

Table Percentage – 57% – 64%
Depth Percentage – 60% – 63%
Girdle – Very Thick to Thin, faceted
Culet – Pointed or None
Polish – Very Good to Fair
Symmetry – Very Good to Fair

There are many popular shapes for diamonds. Each shape affects the overall look, fire and brilliance of the diamond. Each shape has different ranges of cutting proportions. For purposes of our discussion, we will concentrate on the round brilliant cut diamond.

 

Color

When we speak of color in diamonds, most people think of the beautiful reds, blues, and yellows we see when a diamond flashes in the sun light. In fact grading a diamond for color means deciding by which amount the diamond’s “body color” deviates from the whitest possible (water like colorless) color. Nature provides a continuous darkening in the tints from white to yellow, white to brown, and white to green. Divisions are determined by the ability of the human eye to separate one tint from an adjacent one that is slightly lighter or darker. This concept should not be confused with the sparkle, brilliance, or scintillation of the diamond.

GIA Gemological Institute of America pioneered the universal grading system in the early 1940’s to supersede all confusing grading systems in use at that time. The GIA color grading classification starts from D, the finest color (colorless), and proceeds through the alphabet to z getting progressively more yellow. A set of master comparison stones calibrated to the exact color of every-other color: E, G, I … is the most reliable method of grading diamonds for color. When compared in a standard viewing box or white folded paper the master stones are placed on either side of the diamond until the stones are sorted into the proper descending color values. This allow for the accurate color grading of the diamond.

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Carat

The word Carat is derived from the Greek word “keration” which is also the Greek name for the Carob tree (Ceratonia Siliqua). In the Middle East, this tree is fairly common and produces pods with seeds. When dried, these seeds turn black and very hard. Ancient merchants discovered the seeds were always uniform in weight and used them for weighing pearls, diamonds and other precious stones. The carat weight was standardized in the 20th century. The United States officially adopted the metric carat in 1913. One carat = .02 grams or 200 milligrams.

Diamonds are sold by carat, (ct.) not to be confused with karat, (kt.), which in the United States refers to gold quality. The carat is a unit of weight, not size. This is an important concept since the specific gravity varies among different minerals. For example, Emerald has a lower specific gravity than diamond. A one-carat emerald is 20% larger than a one-carat diamond. Ruby has a higher specific gravity than diamond, which makes a one-carat ruby smaller than a one-carat diamond.

Everyone first asks what size is the diamond? Most times color, cut, and clarity seem of secondary importance. It is very important to realize that small shifts in quality and size can make tremendous differences in value. As the size of the diamond increases, the price increases significantly. Diamonds weighing two-carats will sell for far more per carat than one-carat diamonds. The price of a diamond tends to increase exponentially as the size increases.

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Clarity

Grading diamonds for clarity is the process for classifying the imperfections, both internal and external. Imperfections are called inclusions when internal and blemishes when external. The term clarity is preferred over purity because purity has a very narrow definition pure or impure. In order to accurately classify clarity in polished diamonds we need to have several levels of clarity. GIA has standardized a simple but detailed system.

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FL – Flawless – These stones have no imperfections inside or on the outside of the stone under the magnification of a loupe of 10X magnification.
IF – Internally Flawless – This grade is awarded to diamonds with no internal flaws and only minor external blemishes. Nicks pits or girdle roughness, not on the table, which could be removed in re-polishing.

 

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VVS1 , VVS2 – Very Very Slightly Imperfect – These stones have very, very small inclusions, which are extremely difficult to see under a loupe of 10X magnification.

 

 

edu-d-vsVS1, VS2 – Very Slightly Imperfect – These stones have very small inclusions, which are slightly difficult to see under a loupe of 10X magnification.

 

 

edu-d-siSI1, SI2 – Slightly Imperfect – These stones have inclusions, which are fairly easy to see under with a 10X magnification, and can be seen with the naked eye.

 

 

edu-d-iI1, I2, and I3 – Imperfect – These stones have inclusions ranging from eye visible to very easily seen to the naked eye.

 

 

Flaws are caused by a shift in the pressure and or temperature during the time when the diamond is being formed. There are many types of imperfections, internal inclusions and external flaws.

Types of Internal flaws or Inclusions

Pinpoints – A small usually whitish dot that is difficult to see. There can be a number of pinpoints – cluster –or a cloud of pinpoints.
Dark Spot – A small crystal inclusion or thin flat inclusion that reflects the light like a mirror.
Colorless crystal – This is a small crystal of diamond, and sometimes-another mineral.
Cleavage – A small cleavage is a crack that has a flat plane, which if struck in a certain direction, could cause the diamond to split.
Feather – This is another name for crack. A feather is not dangerous if small and does not open through a facet.
Bearding or girdle fringes – Result from hastiness in the bruiting process when giving the diamond its initial shape in the cutting process.
Growth or grain lines – These can only be seen when rotating the diamond slowly during examination. They appear and disappear usually instantaneously and will appear in groups.
Knaat or twin lines – Slightly raised dot with a trail resembling a comet.
Laser treatment – A laser is used to make flaws less visible. A black spot can be vaporized and will disappear leaving a void in the diamond.

Types of External flaws or Blemishes

Natural – This usually occurs on the girdle and looks like a rough, unpolished area. A natural is a remnant of the original skin of the diamond. Indicates a shortage of rough or that the cutter made the largest acceptable diamond from the material he had to work with.
Nick – This is a small chip, usually on the girdle and can be caused by wear. Sometimes a nick or chip can be seen on the edge of a facet.
Girdle roughness – This blemish appears as crisscrossed lines, and can be removed by re-polishing.
Pitts or cavities – Pits or holes on the table facets.
Scratch – A scratch is usually a minor defect that can be removed by re-polishing.
Polishing lines – Many diamonds exhibit polishing lines and are the result of badly maintained polishing wheels.
Abraded or rough culets – The culet has been chipped or poorly finished.