Genuine and fake calcification 如何區別古玉之自然鈣化與偽造鈣化

The phenomenon of calcification is believed to be caused by decomposing the structural water of the jade. The cause of decomposition may be from the interaction of heat and the pressure of the environment where the jade is buried.  Another explanation is that calcification is caused by the interaction of the jade and the surrounding calcium where the antique jade buried. Most people tend to in favor of this kind explanation of jade calcification before any scientific proof has been found. It should be noted that fake calcification jades are often found in fake jades. 一般認為古玉鈣化的形成原因, 可能是起因於古玉解構水之分解. 而古玉解構水之分解可能是受到古玉埋藏環境地熱及地底壓力之影響所致. 另外一種解釋可能是受到埋藏古玉附近的鈣原素影響, 而許多研究者傾向於後者的解釋. 值得注意的是, 偽古玉大多從鈣化作偽進行.






How to Authenticate Jade Artifacts Without Unearth Report?

dsc05271aIt is believed that the quantity of jade artifacts without unearth report is far greater than those  with unearth report. As a result, the chance to authenticate jade artifact without unearth report is quite often.  As mentioned in the handbook in this website, jade authentication involves medium identification, antiquity evidences identification and period identification. As far as jade authentication is concerned, the availability of unearthed report is only relevant to period identification. It is not easy to identify the period of jades under the condition of without supporting evidences such as scripts appeared on the jades or any documents relevant to the particular jade. In addition, there are no standard or universally accepted methods of jade authentication without unearthed report for the present time.  Topological attributes comparison methodology is proposed here before any trustworthy method has already been accepted  by most of the people.

The topological attribute comparison methodology contains the following three procedures:

First, we select a sample jade artifact either with unearth report or has been identified by the public museum that was designated as a specific period

Second, we list as many topological attributes of the sample as we can. These attributes cover the antiquity phenomena due to chemical and physical factors, the motifs, carving style, craftsmanship  and hole drilling pattern described earlier in this handbook.

Third, we map the attributes of the item to be identified with those of the sample item. If we end up with all the attributes matched, then we can infer that the item to be identified should be from the same period of the sample item.

0011-2The percentage of the attributes matched may be used as the probability of the object under investigation is from the same period. For example, if 90% of the attributes matched, then we can infer that the item to identify has a probability of 90% from the same period of the sample item. For the safe consideration, at least 70% is required to be confident that the item to be identified can be inferred from the period of the sample item .

If the period of the jade artifact to be authenticated has no reference jade artifact with unearth report, then we may use artifacts of different material such as bronze which has scripts to find the clues.  For example, we have applied this method for the authentication of the Shin dynasty (AD. 8-25) Octagon-shape Jade Container with Dragon and Phoenix Motif and Inscriptions. For jade seal, the Authentication should be based on the scripts on the base and the style of motifs such dragon & phoenix of the handle.

These is one interesting nonscientific method used by Chinese seasoned jade collectors is referred as hand feeling method. The method used is to rub the jade for several times with thumb to see whether it is shining and have an oiliness but not sticky feeling. If it is shining and oily, it is antique jade. If the jade is not shining and astringent, then it is modern. That is why many Chinese experts insist on touching the jade by hand to believe instead of only seeing it.  They also claim that only studying the documents and the visiting the museums without investigating your own collection will not make you a real antique jade expert.

It should be noted that many private museums in China of recent years may collect fake items. Even public museums, sometimes the collection procedure is not so strict, in the case of Han’s seal of an empress is one example, in my opinion.

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