Standard Methods for Testing Fei Cui for Hong Kong and Definition of Fei Cui
Foreword
This Standard Methods for Testing Fei Cui for Hong Kong presents the recommended standard methods for testing of Fei Cui for gemstone identification and verification purposes in Hong Kong. This Standard has been issued on 19 February 2016 and is published by The Gemmological Association of Hong Kong Limited (GAHK).
This Standard has been prepared by a working group consulting with gemmologists and academics who are experts in this field from Mainland China and around the world. To ensure its acceptance as a consensus document in Hong Kong, a draft version of this standard was widely circulated to relevant gemstone and jewellery trade associations and their opinions were sought. A number of useful comments were received, and these have been taken into account in finalizing this Standard. All such contributions are gratefully acknowledged.
Those working in the gemstone industry are encouraged to send their comments on the contents of this standard to GAHK, so that improvements may be made in future editions.
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Introduction
Fei Cui (Chinese: 翡翠) is a family name that is applied to three related and often visually similar members – Jadeite Jade, Kosmochlor Jade and Omphacite Jade. Accredited Fei Cui test reports are in great demand especially during the auction season. In order to assist both the Fei Cui trading industry and gem testing laboratories to benefit from this increasing demand and to enhance the credibility of the local gemstone industry, this document has been developed and is issued by GAHK with a view to regularising the following:
[1] The practice and methodology of Fei Cui (green, black, white and colourless) testing,
[2] The technical specifications to be set and the formats and contents to be used when issuing Fei Cui test reports or test certificates, and
[3] The definition and nomenclature of Fei Cui.
A companion standard will cover the Fei Cui testing.
Definition of Fei Cui - Jadeite Jade / Omphacite Jade / Kosmochlor Jade
Fei Cui is a granular to fibrous polycrystalline aggregate, which is composed solely, or principally of any of the following or any combination of the following: Jadeite, Omphacite and Kosmochlor.
Fei Cui, Jadeite Jade is a granular to fibrous polycrystalline aggregate. Its major mineral component is Jadeite (NaAlSi2O6). Other minerals such as Omphacite and Kosmochlor may also be present.
Fei Cui, Omphacite Jade is a microgranular to microfibrous polycrystalline aggregate. Its major mineral component is Omphacite [(Ca,Na)(Mg,Al)Si2O6]. Other minerals such as Jadeite and Kosmochlor may also be present.
Fei Cui, Kosmochlor Jade is a granular to fibrous polycrystalline aggregate. Its major mineral component is Kosmochlor (NaCrSi2O6) . Other minerals such as Jadeite and Omphacite may also be present.
When there is a need to differentiate of the three Fei Cui members : Jadeite Jade, Omphacite Jade and Kosmochlor Jade. The Fei Cui Infrared Spectrum Fingerprint Identification Testing Method in Appendix 3 is considered diagnostic and is recommended as a means of distinguishing between the three Fei Cui members. A diagrammatic flow chart of the testing procedures for the classification of the types of Fei Cui is provided in Appendix 1 for the use of laboratories.
Major Physical Properties of Fei Cui - Jadeite Jade / Omphacite Jade / Kosmochlor Jade
Notes:
1. Tests for lustre and hardness are not within the scope of the Standard Methods for Testing Fei Cui for Hong Kong.
2. The standard testing method of Determination of Specific Gravity is not applicable for mounted Fei Cui.
3. The range of Specific Gravity results may vary because of the texture of Fei Cui and the presence of associated minerals.
Natural Fei Cui and Treatment Types
Notes：
1. To polish natural Fei Cui with colourless wax, which does not cause any damage to the crystalline structure of the Fei Cui, shall not be classified as a chemical treatment.
