It’s time to get back into our diamond talk that left off inconclusive last year, without further ado here are two links to refresh your memories about diamonds formation and mining.
Now lets get into diamond grading, there are many laboratories who offer diamond grading worldwide, here are to name a few of the ones that are most heard of:
GIA (Gemological Institute of America)
EGL (European Gemological Laboratory)
IGI (International Gemological Institute)
I am not going to get into details of how these labs work in grading stones but GIA has the highest consistency and standard in grading, therefore is the most reputable and trusted laboratory following by HRD Antwerp.
Now back to grading itself, after diamonds are mined and sort through the sorting system, they are offered in tenders by mining companies for buyers to offer the best price in acquiring a rough diamond. After acquiring the rough, it goes to different manufacturing facilities from Israel to India, Russia, UAE and many more countries. After planning, cut and polish the polished diamond is send off to a diamond grading laboratory to receive its certificate, having the certificate number is laser inscribed on the girdle of diamond for future tracking. All certificate numbers can be looked up on laboratories websites.
4Cs: the 4Cs of diamond quality is the universal method for assessing the quality of any diamonds, created by GIA
4Cs of Diamond Quality by GIA
Color: in diamonds, diamond color means lack of color; absence of color in a diamond makes it a gem quality diamond. A chemically pure and structurally perfect diamond has no hue. GIA D-Z color grading system measures the degree colorlessness by comparing the diamond under controlled lighting and precise viewing condition to master stones of established color value. Many of the color distinctions are so subtle that are invisible to naked (untrained) eye but those distinctions can have a very large impact on the quality and therefor the price.
GIA D-Z Color Scale
Colorless D-E-F
Near Colorless G-H-I-J
Faint K-L-M
Very Light N-O-P-Q-R
Light S-T-U-V-W-X-Y-Z
Clarity: Diamond clarity refers to absence of inclusions and blemishes. during formation of diamond a variety of internal characteristics called ‘inclusions’ and external characteristics called ‘blemishes’ occur in a diamond.
To evaluate diamond clarity, first we need to determine the number, size, relief, nature, and position of these characteristics, as well as how these affect the overall appearance of the stone. The closer a diamond comes to perfectly pure (absolute absence of inclusions and blemishes), the higher its value.
GIA Clarity Scale
GIA Clarity Scale has 6 categories, with some divided in total there are 11 specific grades:
- Flawless (FL) No inclusions and no blemishes visible under 10x magnification
- Internally Flawless (IF) No inclusions visible under 10x magnification
- Very, Very Slightly Included (VVS1 and VVS2) Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
- Very Slightly Included (VS1 and VS2) Inclusions are observed with effort under 10x magnification, but can be characterized as minor
- Slightly Included (SI1 and SI2) Inclusions are noticeable under 10x magnification
- Included (I1, I2, and I3) Inclusions are obvious under 10x magnification which may affect transparency and brilliance
Flawless & Internally Flawless
VVS 1,2 / VS 1,2
SI 1,2 / I 1,2,3
Cut: Diamonds are known for transmitting light and sparkle intensely therefore a diamond’s cut is crucial to the interaction of diamond’s facets and light. Diamond’s cut is the most complex and technically difficult to analyze. It is pure artistry and workmanship to cut a diamond that its proportions, symmetry and polish deliver the maximum return of light and create desirable visual effects such as:
- Brightness: Internal and external white light reflected from a diamond
- Fire: The scattering of white light into all the colors of the rainbow
- Scintillation: The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond
Often a diamond’s cut is mistaken with diamond’s shape but diamond’s cut grade is about how well a diamond’s facets interact with light. 
Diamond CutThe distance from the bottom of the girdle to the culet is the pavilion depth. A pavilion depth that’s too shallow or too deep will allow light to escape from the side of the stone or leak out of the bottom. A well-cut diamond will direct more light through the crown.
Excellent
Very Good
Good
Fair
Poor
Diamond’s cut grade only applies to round brilliant diamond, for the rest if fancy shapes (any shape beside round brilliant is considered a fancy shape) due to their complexity in facets and steps only grading for polish and symmetry is available.
Carat:Diamond carat weight is the measurement of how much a diamond weighs. A metric “carat” is defined as 200 milligrams. Each carat is subdivided into 100 ‘points.’ This allows very precise measurements to the hundredth decimal place.
Diamond Carat Weight
“ALL IMAGES ARE COURTESY OF GIA.edu“
mikejonson
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