Laboratory

We can see in a gemstone what you cannot

        Gem Testing Laboratory Athens (GTL Athens) was founded in 1989 in order to assist mainly the gem and jewellery trade. Members of the public may use our services only via a gem or jewellery trade member. Over the years GTL has gained trade confidence and is reputed for its integrity and independence.

        Our services include the issue of diamond reports, colored stone reports, pearl reports, and verbal trade assessments of color, clarity, and cut. Advise is given about the importance of color, clarity, cut, and carat weight, as well as if a diamond can be improved by repolishing.

        A gemstone can be modified and/or enhanced at any time. Therefore, GTL can reconfirm at any time that the stone is in accordance with the gemstone report.

Diamond Grading

        Reports are issued for loose or set diamonds using the rules of the International Confederation of Jewellery, Silverware, Diamonds, Pearls and Stones (CIBJO). Grading is determined by an experienced expert under an adequate light source. Clarity grading is determined using a 10 X magnification corrected loupe. Color grading is determined by means of comparison with a diamond master set.
   

COLOR GRADING SCALE

CIBJO *

GIA**

Exceptional White +

D

Exceptional White

E

Rare White +

F

Rare White

G

White

H

Slightly Tinted White

I

J

Tinted White

K

L

Tinted Color 1-4

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

CLARITY GRADING SCALE

CIBJO *  Loupe Clean VVS1 VVS2 VS1 VS2 SI1 SI1 P1 P2 P3
GIA** FL IF VVS1 VVS2 VS1 VS2 SI1 SI2 I1 I2 I3
Picture1(2)
clarity
colour
lab4

* International Confederation of Jewellery, Silverware, Diamonds, Pearls and Stones

** Gemological Institute of America

Colored Stones

        All types of gemstones are tested in order to identify the species and to differentiate between natural gemstones and their synthetics and simulants together with the varius treatments used.

Pearl Identification

        Using direct radiography, X-ray diffraction and optical techniques, the GTL can distinguish between natural pearls, non nucleated or beaded cultured pearls and imitation pearls.

Fees

        GTL will conduct any examination for a fee. Fees depend mainly on the weight in carats of the stone(s) examined. Before submitting any item(s) for examination, please contact our laboratory for further information.