Different gem labs grade clarity in colored gemstones differently. Cowdisley uses the GIA (Gemological Institute of America) Colored Gemstone Grading Scale. According to the GIA – perhaps the world’s best known and trusted Gem Association and Lab, there are THREE different charts for grading colored gemstones (and Diamonds). Perhaps the one that most jewelers are familiar with is the Type 1 Gemstone Chart, which includes the grading of Diamonds. The Chart that a gemstone is graded in is dependent on the physical characteristics of the majority of a particular gemstone; such as Ruby being graded as a Type 2.. The charts and the gemstones that fit into each are as follows:

	TYPE I Usually eye clean Aquamarine, Chrysoberyl, yellow and green, Heliodore, Morganite, Quartz, smoky, Spodumene, all Tanzanite, Tourmaline, green, Zircon, blue	TYPE II Usually included Andalusite, Alexandrite, Ruby, Sapphire, all,Garnet, all Iolite, Peridot, Quartz, ametdyst, citrine, ametrine, Spinel, all, Tourmaline, all but green, red and watermelon, Zircon, all but blue	TYPE III Almost always included Emerald, Red Beryl,Tourmaline: red and watermelon
VVS	Minute inclusions, difficult to see under 10X. Eye clean.	Minor inclusions, somewhat easy to see witd 10X. Usually eye clean.	Noticeable inclusions under 10X. Usually eye clean.
VS	Minor inclusions, somewhat easy to see witd 10X. Usually eye clean.	Noticeable inclusions under 10X. May be eye visible.	Obvious inclusions witd 10X. May be eye visible.
SI1	Easily noticeable witd 10X. Slightly visible to tde unaided eye. Usually low relief.	Obvious inclusions, large or numerous under 10X. Apparent to unaided eye.	Prominent to unaided eye.
SI2	Easily visible to tde unaided eye. Usually low relief.	Obvious inclusions, large or numerous under 10X. Very apparent to unaided eye.	Very prominent to unaided eye.
I1	Moderate effect on appearance or durability.	Moderate effect on appearance or durability.	Moderate effect on appearance or durability.
I2	Severe effect on appearance or durability.	Severe effect on appearance or durability.	Severe effect on appearance or durability.
I3	Severe effect on both appearance and durability.	Severe effect on both appearance and durability.	Severe effect on both appearance and durability.
Dcl	Not transparent	Not transparent	Not transparent

 

 

Gemstone Enhancement Codes

N	F	G	H	O	T	D	HL
None	Filling, Infilling or Stabilizing	Irradiation	Heat Enhancement	Oiling/Resin Infusion	Treated (berylium)	Dyed	Heat Enhancement/Lattice diffusion

 

---

The GIA nomenclature also specifies six levels of saturation ranging from "grayish" (neutral grey) to "moderately strong" to "vivid." The term "intensity" is also used to describe a stone's saturation. Gemstone Saturation Chart To describe the darkness or lightness of a colored stone, the GIA system has nine levels of tone ranging from "very very light" to "very very dark." A numerical value is assigned to each label for use in a grading report. Gemstone Tone Chart

«	Australian owned with US and Canadian Representation.
«	All Gemstones are Inspected and Photographed by Cowdisley.
«	Inspection and Return Policy after Seven Days.
«	Fluent English Speaking and Writing Customer Support.
«	Impartial Advice Regarding your Purchases.
«	Secure On-line Payments.
«	Fast and Secure Shipping Options.
«	Our Business relies on Customer Satisfaction.

Customer Satisfaction: If for any reason you are not completely satisfied with your purchase please send us an email stating your concerns and we will try to solve the problem. Returns are accepted for legitimate reasons within 7 days of delivery. Returns must be approved via email and an RGA (Return of Goods Authorization) code must be given prior to returning any item. Specific return instructions will be provided along with RGA code. 

BACK TO JEWLERY HOME