Quality Grading  >> http://www.GanpatiJewelsJaipur.com

GIA colored gemstone grading system

The same "four Cs" that establish quality in Diamond are used for colored gemstones: cut, carat weight, clarity and most importantly, color.

Color: The more pure and vivid the color, the more valuable the gemstone.

Cut: All gemstones must be cut well to attain their maximum potential for beauty. Quality cutting is what produces the brilliance and scintillation that captures the eye of the beholder.

Clarity: Gemstones contain characteristic inclusions that provide proof of their natural origin. Those inclusions should not be so visible that they detract from the beauty of the gemstone.

Carat Weight: Obviously, larger gemstones are more rare. However, some gemstones, such as Amethyst and Tourmaline, routinely occur in very large sizes while others, such as Ruby and Sapphire, rarely occur in sizes above 2 to 3 carats.

COLOR:
Considered the most important. Each gemstone has its own specific colors, and each has its most desired color which will vary from one geographic area to another. Generally the richer (darker, but not too dark) and brighter the color and the more even color distribution, the prettier and more expensive the gemstone will be. The duller, more zoned and lighter colored gemstone will usually be more reasonable. Color grade can be 70% of the total value of the gemstone.

Hue:
The essential impression of color that we notice immediately (Red, Blue, Greenish Yellow, etc)

Tone:
The color's lightness or darkness. (Light, Medium, Dark)

Saturation:
Purity of the color. The more grayish or brownish, the lower the saturation and the duller the color. Gemstones that have real dark tone, or real light one (washed out) never reach a high saturation. The desired appearance is appealing and bright and could be called "Vivid".

Vivid-Bright (6)  5         Medium (4-3)  2     Dull Brown-Gray (1)

CUT:
(Quality/Polish/Finish) - Excellent (10 - 8) Very Good (7 - 6) Good (5 - 4) Fair (3 - 1)


CLARITY:
The degree of freedom from visible characteristics put there by Mother Nature during the stone's growth. Clarity grades for colored gemstones are categorized into three areas: Type I that are generally very clean and are penalized more than Type II for having any inclusions and Type III, where inclusions are expected and not penalized as heavily as Types I & II.

Type I
Aquamarine, Chrysoberyl, Citrine, Topaz, Smoky Quartz, Green Tourmaline, Tanzanite and Blue Zircon.

Type II
Alexandrite, Amethyst, Garnets, Peridot, Iolite, Ruby, Sapphire, Spinel, all Tourmaline except red and green.

Type III
Emeralds, Red & Pink Tourmalines.

VVSI - Very, Very Slightly Included (the best) Minute inclusions that are difficult to see using 10X, and are not visible at all to the naked eye.

VSI - Very Slightly Included Minor inclusions that are easier to see using 10X, but still not visible to the naked eye.

SI1 - Slightly Included I The inclusions are easily seen using 10X, and are noticeable with the naked eye.

SI2 - Slightly Included 2 The inclusions are more easily seen using 10X, and are quite visible with the naked eye.

I1 - Included 1 The inclusions are very obvious and they have a moderate negative effect on the over-all appearance or durability of the gemstone.

I2 - Included 2 The inclusions are very obvious and they have a severe negative effect on the over-all appearance or durability of the gemstone.

I3 - Included 3 The inclusions are very obvious and they have a severe negative effect on both the over-all appearance and durability of the gemstone.

Declasse - stones not transparent because of inclusions

 

COLOR & CLARITY GRADING

COLOR

CLARITY

Extra Fine (10 - 9)

Top known color for its variety
Even distribution-optimal tone & vivid

Type

I

Flawless under 10x

 

II

Very slightly included under 10x

 

III

Not included to the eye

 

Fine  (8 to 7)

Highly desirable - strong saturation

Type

I

Very slightly included under 10x

 

II

Slightly included under 10x

 

III

Very slightly included to the eye

 

 

Good  (6 to 4)

Desirable - some zoning
Some extinction - Moderate saturation

Type

I

Slightly included under 10x

 

II

Included under 10x becoming visible to the eye

 

III

Slightly included to the eye

 

Commercial (3 to 1)

Fair to Good Heavy Zoning & Extinction
Gray or brown saturation

Type

I

Heavily included under 10x

 

II

Visible inclusions to the eye

 

III

Included to the eye

Gemstone quality grading at Ganpati jewels are drived from above described colored gemstone grading system of GIA

Below mentioned scale define Clarity, Color ,Cutting & Overall Quality Grading At Ganpati jewels.

Clarity

Clarity Scale 

VVSI1

VVSI2

       VSI1     VSI2

SI1

SI2

I1

I2

I3

 

 

very slight Inclusions 1 very slight Inclusions 2

Slight Inclusions 1

Slight Inclusions 2

Included 1

Included 2

Severely included

 
Color

Color Scale

AAA

AA

A

LS

VLS

Excellent

Very Good

Good

Light Shade

Very Light Shade

 
Cutting and Finishing

Cutting and Finishing Scale

10-9

8-7

6-4

3-1

0

Super Fine

Very Good

Good

Fair

Poor

 
Overall Quality Grading
Below is scale, which defines Overall Quality of Gemstone and Beads at Ganpati Jewels

Quality Grading Scale

AA

A

              AB

B

C

DCl

Super Fine Quality

Vary Good Quality

    Good Quality

Average Quality

Low Quality

Very Low Quality

 

 

 

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