The above Certificate of Jade Identification is done by the Hong Kong Jade & Stone Laboratory on one of the floral jade that I sent in previously.
HKJSL is a reputable and independent jade and gemstones laboratory and I often send jade for their identification. They are very professional and their certificates issued are accepted and highly regarded by all jade and gems dealers. Often, HKJSL issues certificates of Jade Identification for high end jade pieces destined for auction at Christie’s and Sotheby in Hong Kong and other international cities.
For jade enthusiast and amateurs, it may be good education to understand the terms and definitions as appeared in a Jade Certificate. Certain testing procedures are necessary but may not be sufficient for a gemologist to conclude the sample’s identity while certain tests are diagnostic to make a conclusive and affirmative call. One of the testing procedure which is mandatory to determine whether a Jadeite Jade is Type A or Type B is to scan the sample with a Fourier Transform Infra-Red Equipment (FTIR) to detect the presence of organic compounds related to the C-H bond. (C for carbon and H for hydrogen)
One has to understand that whatever tests conducted and stated in a jade, diamond or gemstones certificate as issued by a gem laboratory must be empirical. That is, if a gem lab concludes that a specific test yields a certain result, then that same test must also be observable when tested in other gem labs.
I have read some jade reports, usually some proprietor-owned lab, that states a certain result which is not based on test being carried out but based on known facts of the identity of the sample. For example, a jade certificate may state that the specific gravity of a mounted ring with jade as the center piece (which is the object to be tested) is 3.32. Yes, the SG of jadeite jade is 3.32 but how does the gemologist carried out that SG test when the stone is mounted?
Hence, some knowledge on the findings of a jade report are useful. A brief run down on each of the item of the Jade Certificate above is described below.
Under the title ‘DESCRIPTION” the item is described as clearly as possible.
Under the title ‘TESTS AND FINDINGS’ :
a) Refractive Index : 1.66.
This result can be obtained by using a Refractometer.
b) Specific Gravity : 3.32
This result can be obtained by using the Hydrostatic method. Since this is an unmounted jade piece and it is quite small, this testing procedure is easily carried out.
c) Fluorescence : L.W – Weak white in patches / S.W – Inert
Natural Jadeite Jade when exposed to Long Wave and Short Wave Ultraviolet light may emit weak white streaks or remains inert. When a jade piece fluorescences strongly then possibly it is an enhanced jade.
d) Spectroscope : Fine chrome lines in the red
The spectroscope is used to analyze light passing through a stone. White light is a combination of all the colors of the visible spectrum: red, orange, yellow, green, blue, indigo, and violet. When white light travels though a gemstone, one or more of the wavelengths that produce color are absorbed by the gem. The colors that are not absorbed are the colors seen when we look at the stone.
The wavelengths that are absorbed by the stone are seen in the spectroscope as vertical black lines in the spectrum. Each gemstone has a unique absorption spectrum (like a fingerprint of the stone) When identifying a stone we look for a spectrum that is characteristic for that stone.
e) Texture by Eye / By Magnification : Fine to medium grain aggregates / Fibrous and granular texture.
These observations conform to the texture of jadeite jade.
f) Under Chelsea Colour Filter : Green
Some dyed jadeite jade may appear reddish under a Chelsea Filter, but not all dyed jade. This is an additional test but is not diagnostic nor conclusive and it shows that procedures undertaken by the gemologist is thorough, exhaustive and well documented.
g) Polymer Detection : No polymer is detected.
Below this description are two charts showing the spectrum as scanned by an FTIR equipment. Both charts are the same, the first chart has the Y-axis as the Percent Transmittance while the second chart has the Y-axis as absorbance. The bell curve on the right is the molecular fingerprint of a jadeite jade. When polymers are detected there are certain peaks and these peaks identified the jadeite jade to be polymer impregnated. There are none shown on the charts.
With all these tests being carried out , the gemologist concluded that the sample tested is Natural Jadeite Jade and the final diagnostic test on the FTIR determined that the jade piece is free from polymer.
Hence, the Conclusion is “Natural Jadeite” with a remark stating that “Sometimes known in the trade as “A Jade”.
Some of the gemological tests on the above are described in my earlier posts. Please use the Search function if you want to be clear on these gemological terms and tests.
In latter posts I shall show you some gem lab reports that are flawed and thus one has to be on the alert for these so-called gemologist.
Acknowledgement : http://prettyrock.com