(Left: Mr. Nicholas Sturman, Mr. Dominic Mok, I and Dr. Danny Lau (HKSTP))
In the beginning, Mr. Kesson Lee (Secretary-General, HKCTC) gave a welcoming remark. He said Hong Kong was the second large market for Jewelry Trade. It was started from OEM to Retail and then to build own brand. Testing and Certification of Gold and Jade would build up customer confidence in Hong Kong.
All guest speakers took a group photo.
The first speaker was Mr. Dominic Mok (Principal, Asian Gemmological Institute) and his topic entitled “Advanced Identification of Gemstones and Diamond”. Firstly, Mr. Mok briefed the natural gemstone included natural diamond and natural coloured gemstone. Then he explained the purpose of Gem Testing which aimed to identify the Natural, Treated and Synthetic Gems.
Then Mr. Dominic Mok mentioned Instrumentation of Gem Testing which separated into Conventional Gemmological Instruments (e.g. Microscope) and Advanced Instruments (e.g. FTIR, EDXRF, Raman, UV-VIS, etc). There were four types of diamonds in the following diagram.
The advanced diamond testing instruments were introduced and they were DiamondSure, DiamondView and DiamondPlus. DiamondSure used to identify Natural Type Ia and provided opinions on Type IaB, Type II, as well as reference for not diamond. DiamondView used very short UV. It identified Type Ia Diamond (with blue fluorescence), Type Ib (with greenish yellow fluorescence) and Type IIa (with bluish green fluorescence) as well as octahedral growth pattern. DiamondPlus was a mini Raman Spectrometer with detection stage cooled by LN2. It used to confirm natural diamond Type IIa and reference to CVD Synthetic or HPHT (High Pressure High Temperture) treatment. After that he stated the UV-Vis Spectrometer with D-N-C Probe which was able to help mounted diamonds as little as 0.01 carats.
The identification of coloured gemtones and pearl (Natural, Cultured with Salt-water & Fresh-water) using advanced instruments (e.g. EDXRF, FTIR, and Cathodoluminescence (CL)) were also discussed. Finally, Dominic mentioned the testing of Jadeite / Fei Cui in which separated into Type A, Type B and Type C, as well as, Type B+C.
Lastly, Mr. Dominic Mok concluded that advanced testing instruments were necessary for testing conclusions including CVD synthetic diamonds, Paraiba tourmaline, Resin-impregnated jadeite / Fei Cui and Synthetic jadeite, etc.
The following diagram showed the Diamond Masters.
After that he discussed the identification of pearl and showed the pearl standard.
The master of pearls was illuminated by X-ray and the concentric meaty nuclei with white core were used as standards.
The first Q&A Session
I asked if digitalized diamond standard could be developed because Diamond Master was very expensive. Both speakers said it could be one of directions.
Mr. K. Gabuji (HKAS Technical Assessor) asked could man-made diamond be detected. Speaker said it was so little case because man-made diamond was very expensive too.
Then I took a photo with my old friend - Gabuji
The third speaker was Dr. Pitar Li (Laboratory Manager, Chow Sang Sang Precious Metal Laboratory) and his presentation topic was “Selection of Appropriate Testing Method for Gold Jewellery”. He briefed the Hong Kong Trade Descriptions (Marking) (Gold and Gold alloy) Order that the main body did not lower than 999 and the solder used is of fineness or not less than 800.
Dr. Li introduced different test methods and separated into Basic and Advance Methods. For Basic Methods, it included Touch Stones (試金石), Density, Electrical Conductivity and XRF (Countertop Gold Testing Machine). For Advance Methods, Cupellation Method (灰吹法), Difference Method using ICP-OES and precise XRF. The following showed some method flows according to specific standards methods.
i) Cupellation Method(ISO 11426:1997)
ii) The Difference Method (ISO 15093:2008) where 17 elements to be measure were Silver, Bismuth, Cadmium, Cobalt, Copper, Iron, Iridium, Manganese, Nickel, Lead, Platinum, Palladium, Rhodium, Ruthenium, Tin, Titanium and Zinc.
iii) "Adornment-provision for limit of baneful elements" (GB/T 28480-2012)
Dr. Li suggested to integrate different test methods was important for a piece of jewellery to fulfill the regulations. Finished jewellery used non-destructive methods and Raw Material before manufacture could be tested for control the jewellery quality.
The last speaker was Prof. Mimi Ou Yang (Principal, The Hong Kong Institute of Gemmology) and her topic entitled “The New Thinkings in Authentication of Fei Cui: The Integration of Advanced Instrumentation and Experience”. Prof. Ou Yang briefed the background of Fei Cui which was difficult to identify in treated Jadeite in the past.
The following diagram showed the natural Fei Cui (Type A) and treated Fei Cui (Type B, C & B+C).
Then Prof. Ou Yang introduced the three key parameters to confirm Jade such as Hardness, Specific Gravity (S.G.) and Refractive Index (R.I.).
Different instruments such as UV, FTIR, LRS, were discussed to assist for confirmation of different Fei Cui. However, Prof. Ou Yang emphasized experience and competence of examiner was more important than instrumentation. The following diagram demonstrated the right way and right thinking in Authentication of Fei Cui.
Reference:
HKCTC - http://www.hkctc.gov.hk/en/home.html
HKCTC Seminar presentation file - http://www.hkctc.gov.hk/en/work_seminars.html#b44
HKAS - http://www.itc.gov.hk/en/quality/hkas/about.htm
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