April – DIAMOND
| CHEMICAL COMPOSITION | C |
|---|---|
| CUBIC CRYSTAL SYSTEM | |
| REFRACTIVE INDEX | 2.417 |
| HARDNESS | |
| SPECIFIC GRAVITY | 3.52 (+.01, -.01) |
| DISPERSION | .044 |
| CLEAVAGE | perfect in four directions |
| GIA GRADING |
Additional Information
Diamonds in a typical color range are compared to previously graded master stones, and are assigned letter grades starting at D (virtually no trace of color), with successive letters corresponding to gradually increasing traces of color, on through to Z (light yellow). When closely examined under 10x magnification, diamonds are assigned the following clarity grades:
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond has the highest hardness and thermal conductivity of any material. Those properties determine the major industrial application of diamond in cutting and polishing tools. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen. Combined with wide transparency, this results in the clear, colorless appearance of most natural diamonds. Diamond also has relatively high optical dispersion (ability to disperse light of different colors), which results in its characteristic luster.
Most natural diamonds are formed at high-pressure high-temperature conditions existing at depths of 140 to 190 kilometers (87 to 120 mi) in the Earth mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years. Diamonds are brought close to the earth’s surface through deep volcanic eruptions by a magma, which cools into igneous rocks known as kimberlites and lamproites.
Diamonds can also be produced synthetically in a high-pressure high-temperature process which approximately simulates the conditions in the Earth mantle. An alternative and completely different growth technique is chemical vapor deposition (CVD).
Several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. GIA techniques can be used to distinguish natural and synthetic diamonds as well as diamond simulants.
The popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising. An important aspect of buying a diamond includes an understanding of the "four Cs" of diamonds which are considered the most important grades and categories:
Cut
Cut is probably the most important of the four Cs. The brilliance of a diamond depends on how it was cut. A good cut gives a diamond its brilliance, which is the brightness that begins at the heart of a diamond. The angles and finish of a diamond are what determine the way it handles light, which leads to brilliance.
Clarity
Most diamonds contain some inner flaws, or inclusions, that occur during the formation process. The visibility, number and size of these inclusions determine what is called the clarity of a diamond. Inclusions include flaws such as air bubbles, cracks, and non-diamond minerals found in the diamond. Blemishes include scratches, pits, and chips. Some blemishes occur during the cutting processes. Diamonds with no or few inclusions and blemishes are more highly valued than those with less clarity because they are rarer.
Color
Colorless diamonds are the most desirable because of their sparkle since they allow the most refraction of light. Off white diamonds absorb light, inhibiting brilliance. To grade 'whiteness' or colorlessness, most jewelers refer to GIA's professional color scale that begins with the highest rating of D for colorless, and travels down the alphabet to grade stones with traces of very faint or light yellowish or brownish color. The color scale continues all the way to Z.
Carat Weight
A carat is the unit of weight for the way a diamond is measured. One carat is equal to 200 milligrams, or 0.2 grams. The word "carat" is taken from the carob seeds that people once used in ancient times to balance scales. These seeds are so uniform in shape and weight that even today's sophisticated instruments cannot detect more than three one-thousandths of a difference between them. Larger diamonds not discovered as often as smaller ones, so large diamonds are rare and have a greater value per carat. Deciding on carat size is really about striking a balance between size and quality. When choosing your setting you have to be sure that the setting you choose is made to fit the carat weight of your diamond.
The Fifth C: Certificates
The diamond certificate, its grading report, is a complete evaluation of your diamond that has been performed by a qualified professional with the help of special gemological instruments. Each stone bears its own recognizable, individual characteristics, which are listed on the certificate.
Appearance:
Misnomers:: none known
Typical Size Range:: melee to about 5 ct; finished stones of several hundred carats exist
Typical Cutting Styles: : faceted
Cleaning Methods:
Diamond Enhancement Information
References
Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
GIA. (n.d.). GIA Grading and Reports. Retrieved July 29, 2011, from Gemological Institute of America:
http://gia4cs.gia.edu/cm/grading-reports.htm
ICGA. (n.d.). All About Gems. Retrieved July 30, 2011, from International Colored Gemstone Association:
http://www.gemstone.org/index.php?option=com_content&view=section&layout=blog&id=1&Itemid=69
IGS. (n.d.). IGS Reference Library. Retrieved July 29, 2011, from Internatonal Gem Society:
http://www.gemsociety.org/info/info.htm
- FI (Flawless)
- IF (Internally Flawless)
- VVS1, VVS2 (Very Very Slightly Included)
- VS1 , VS2 (Very Slightly Included)
- SI1 ,SI2 (Slightly Included)
- SI1 ,SI2 (Included)
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond has the highest hardness and thermal conductivity of any material. Those properties determine the major industrial application of diamond in cutting and polishing tools. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen. Combined with wide transparency, this results in the clear, colorless appearance of most natural diamonds. Diamond also has relatively high optical dispersion (ability to disperse light of different colors), which results in its characteristic luster.
Most natural diamonds are formed at high-pressure high-temperature conditions existing at depths of 140 to 190 kilometers (87 to 120 mi) in the Earth mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years. Diamonds are brought close to the earth’s surface through deep volcanic eruptions by a magma, which cools into igneous rocks known as kimberlites and lamproites.
Diamonds can also be produced synthetically in a high-pressure high-temperature process which approximately simulates the conditions in the Earth mantle. An alternative and completely different growth technique is chemical vapor deposition (CVD).
Several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. GIA techniques can be used to distinguish natural and synthetic diamonds as well as diamond simulants.
The popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising. An important aspect of buying a diamond includes an understanding of the "four Cs" of diamonds which are considered the most important grades and categories:
- Cut
- Clarity
- Color
- Carat Weight
- Certificates
Cut
Cut is probably the most important of the four Cs. The brilliance of a diamond depends on how it was cut. A good cut gives a diamond its brilliance, which is the brightness that begins at the heart of a diamond. The angles and finish of a diamond are what determine the way it handles light, which leads to brilliance.
Clarity
Most diamonds contain some inner flaws, or inclusions, that occur during the formation process. The visibility, number and size of these inclusions determine what is called the clarity of a diamond. Inclusions include flaws such as air bubbles, cracks, and non-diamond minerals found in the diamond. Blemishes include scratches, pits, and chips. Some blemishes occur during the cutting processes. Diamonds with no or few inclusions and blemishes are more highly valued than those with less clarity because they are rarer.
- F Flawless: No internal or external flaws. Extremely rare.
- IF Internally Flawless: no internal flaws, but some surface flaws. Very rare.
- VVS1-VVS2 Very Very Slightly Included (two grades). Minute inclusions very difficult to detect under 10x magnification by a trained gemologist.
- VS1-VS2 Very Slightly Included (two grades). Minute inclusions seen only with difficulty under 10x magnification.
- SI1-SI2 Slightly Included (two grades). Minute inclusions more easily detected under 10x magnification.
- I1-I2-I3 Included (three grades). Inclusions visible under 10x magnification AS WELL AS to the human eye.
Color
Colorless diamonds are the most desirable because of their sparkle since they allow the most refraction of light. Off white diamonds absorb light, inhibiting brilliance. To grade 'whiteness' or colorlessness, most jewelers refer to GIA's professional color scale that begins with the highest rating of D for colorless, and travels down the alphabet to grade stones with traces of very faint or light yellowish or brownish color. The color scale continues all the way to Z.
Carat Weight
A carat is the unit of weight for the way a diamond is measured. One carat is equal to 200 milligrams, or 0.2 grams. The word "carat" is taken from the carob seeds that people once used in ancient times to balance scales. These seeds are so uniform in shape and weight that even today's sophisticated instruments cannot detect more than three one-thousandths of a difference between them. Larger diamonds not discovered as often as smaller ones, so large diamonds are rare and have a greater value per carat. Deciding on carat size is really about striking a balance between size and quality. When choosing your setting you have to be sure that the setting you choose is made to fit the carat weight of your diamond.
The Fifth C: Certificates
The diamond certificate, its grading report, is a complete evaluation of your diamond that has been performed by a qualified professional with the help of special gemological instruments. Each stone bears its own recognizable, individual characteristics, which are listed on the certificate.
Appearance:
- Usually a very light yellow, brown, or gray to colorless; more rarely, gem diamonds occur in fancy colors, which include darker yellows, browns, and grays, and very light to dark tones of blue, green, orange, pink, red, and purple; black stones are occasionally cut as gems
- Transparent to opaque
- Phenomena: Adamantine luster
- Waxy to granular girdle surface; bearding; sharp facet junctions; angular inclusions; thermal conductivity higher than all stimulants. Spectra can be used to identify irradiated stones.
Misnomers:: none known
Typical Size Range:: melee to about 5 ct; finished stones of several hundred carats exist
Typical Cutting Styles: : faceted
Cleaning Methods:
- Ultrasonic: Usually safe, unless contains feathers
- Steamer: Usually safe, unless contains feathers
- Warm soapy water: safe
Diamond Enhancement Information
References
Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
GIA. (n.d.). GIA Grading and Reports. Retrieved July 29, 2011, from Gemological Institute of America:
http://gia4cs.gia.edu/cm/grading-reports.htm
ICGA. (n.d.). All About Gems. Retrieved July 30, 2011, from International Colored Gemstone Association:
http://www.gemstone.org/index.php?option=com_content&view=section&layout=blog&id=1&Itemid=69
IGS. (n.d.). IGS Reference Library. Retrieved July 29, 2011, from Internatonal Gem Society:
http://www.gemsociety.org/info/info.htm
