HomeProblems associated with the identification of B-jade and FTIR Spectroscopy
Problems associated with the identification of B-jade and FTIR Spectroscopy

Problem associated with the identification of B-jade

Gemmological methods:

Index of Refraction:

No difference between natural and treated jadeite

Absorption Spectrum:

No difference between natural and treated jadeite

Appearance:

Immersing the treated jadeite in acetone for 30 minutes shows no visible change in appearance. No effect is observed after immersion in alcohol for five minutes. Alan Hodgkinson used a small drop of pure HCl on a piece of natural jadeite, he observed sweating effect.

However But on the treated jadeite there was no sweating appearance observed in B-Jadeite Jade because the pores are filled with polymer. Again the sweating effect depends on the surrounding i.e. the temperature and humidity of the air. Filler can be seen in fissures or surface reaching fractures. Poor lustre could be observed in low quality jadeite and white spots were evident on some pieces. In a number of pieces of gas bubbles could be seen along the fractures of the jadeite, or polymer could form puddles in shallow, concave area.

Reaction to the Thermal Tester:

Some of the sample showed sweating effect, under microscope, when the probe touches the surface of the untreated jadeite. This is due to the residual wax. The surface of B-jade on contact with hot point releases plastic odor and some melting. This is a potentially destructive test(if the sample turns out to be B-jade or some other plastic imitation) and therefore not a very good test.

Specific gravity (S.G.):

Most natural jadeite sinks in 3.32 liquid because the S.G. of natural jadeite is 3.34 or more. But some natural jadeite jades may be considerably lighter due to an admixture of amphiboles. S.G. of the jadeite that has been bleached shows a range from 3.22 to 3.25. Those that are bleached and polymer impregnated floated in the 3.32 liquid i.e. range from 3.04 to 3.27. This lower S.G. range is attributed to the replacement of iron compounds by relatively lighter organic polymers. Some polymer impregnated jadeite did not sink in the S.G. liquid. It was concluded that S.G. is not a reliable test.

 

Ultraviolet luminescence:

Most natural, untreated jadeites are inert to ultraviolet radiation with some fluorescing a faint to moderate yellow in white areas under LW. All the polymer impregnated jadeite fluoresce a faint to strong bluish white to yellowish green luminescence. More recently many of the B-jade tend not to fluoresce under LWUV.

 

Sound effect:

This method apply only to bangles. Using a string to hold a bangle, lightly tap the bangle with a 2 cm diameter coin. Natural jadeite rings a clear sound whereas B-jade emits a duller, more muffled sound. The reason that for B-jade to sounds dull and muffled is because the interlocking grain structure has been damage to a certain extent during the bleaching process. Some manufacturers use a certain type of polymer to bond the interlocking grain structure, thus giving the jade bangle a better sound effect. Using sound effects to determine the nature of jadeite jade is therefore an unreliable method.

For sound effect, use a coin to strike lightly at the bangle

 

Advanced Testing

Infrared Spectrometer - Please read article on Jadeite Jade and FTIR

 

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