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Age and Quality of Jade


#1

Is is possible to judge the age of jade sculptures by the ammount of
white residue (calcification?) in the recesses and possible by the
pitting of the surface?

Can somebody recommend a good reference book on jade, the types and
the quality criteria?

Thanks,
Dietrich


#2

Hi Dietrich Identification of the age of jade sculptures by the
amount of white residue can be quite risky. Because I have seen new
jade material treated to look like old one. Treatment could involved
burying the jade carving in soil and then pour acid or alkaline
solution into the soil. One of the technique mentioned by jade
carvers. An old jade professor used to work for the Forbidden City,
Beijing jade collection section once told me, you need to study the
Chinese history inorder to understand the jade carving. The reason
is that each dynasty produced certain unique carving technique or
style and you have about 5,000 years of Chinese history to study. I
was told again that sometime a jade carving may looks like 12th
century style but found later to have copied during the 16th century.
Most of the modern jade carving has better polish, style could be
copied and technique of carving is quite different because the new
tools used to do the carving. Technique of carving has improved over
the years, so you need to observe the modern again ancient jade
technique. May be you can talk to museum people who handle jade in
your country?

Regarding about books on jade especially on carving, unfortunately
many of the jade books are in Chinese language. One recent
publication under the title “Jadeite-jade” was by OuYang C. M. in two
volumes (in Chinese.) There is one just came out in English version
under the same title and same author but shorter version. Write to
Mdm OuYang, email: cmouyang@my.netvigator.com

English text, please read Webster, R. (1997), Gems: their sources,
description and identification. 5th edition, p 276-279. Another one
is by Geoffrey Wills " Jade of the East". or a summary of jade
treatment written by this author “Disclosure - Gemstones &
synthetics : Does the jewellery industry care?” by Tay Thye Sun,
lecture presented at the APEC 2000 International Jewellery
Conference, Melbourne, Australia, published in The Australian
Gemmologist, (2001), 21, p67-75, you can write to Dr. Grahame Brown,
the editor of the Australian Gemologist email: austgem@gil.com.au for
the paper.

Regards,
Tay
www.gem.com.sg


#3

Hello Tai, thank you very much for your detailed answer, which I
summarize as follows:

  1. White residue on jade sculptures should not be used as age
    indicator because it can be artificially created.

  2. During the course of Chinese history, the style of art objects
    changed. However, styles can be copied and are, therefore, not
    reliable indicators for the age of jade sculptures.

  3. Carving methods and tools have evolved. Craftsmen use the tools
    of their time. The evaluation of carving methods used for a sculpture
    is the best approach to estimating its age. For that, it is necessary
    to study the history of jade-carving tools and methods.

Please correct my summary where required. Thanks again, Dietrich


#4

Hi Dietrich

  1. & 2. is all right. 3. need modification.
1. White residue on jade sculptures should not be used as age
indicator because it can be artificially created.
2. During the course of Chinese history, the style of art objects
changed. However, styles can be copied and are, therefore, not
reliable indicators for the age of jade sculptures.
3. Carving methods and tools have evolved. Craftsmen use the tools
of their time against modern tool are quite different.  In addition,
it is necessary to study of Chinese history in jade carving.

The best part of education is through archeological work. When the
tombs of an emperor or his subject were just discovered, the expert
will be there to evaluate the many other artifact besides jade. They
have to take note of arrangement or positioning of the jade object
next to the emperor / subjects; type of jade material (it could be
stone object too); the extend of preservation; jade in relation to
other artifact; the size, colour, type and style of jade carving;
and many more interesting need to be recorded. Through
this exercise of cataloging, the expert will know just by looking the
jade object that it belongs Ching, Han, Song dynasty, etc. I am
still learning anyway and this is just a small part of the learning.

Regards,

Tay


#5

Is is possible to judge the age of jade sculptures by the ammount of
white residue (calcification?) in the recesses and possible by the
pitting of the surface? Jade is not a calcite, it is NaAlSi2O6, you
may want to check if it is Nephrite which is Ca2(Mg,Fe)5 Si8O22(OH)2
that would affect the price alot.

Aaron A Tracy


#6
Is is possible to judge the age of jade sculptures by the ammount
of white residue (calcification?) in the recesses and possible by
the pitting of the surface? 

residues of this, and many other types, are also fairly easy for
forgers to fake, and jades have long been a frequent target of such
efforts.

Peter