Jadeite: impregnated and dyed
First published in Facette 28 (May 2023)
Jadeite-jade of saturated emerald green colour is highly valued in Asia. It is therefore not astonishing to see in the market either heavily treated jadeite-jade or even imitations made of different minerals which pretend to be fine quality jadeite-jade of “Imperial green” colour.
An exemplary case was submitted last year, being a ring of 25 mm diameter and showing a vivid green colour as is known in chromium- bearing jadeite. A closer look however revealed distinct colour concentrations in fissures and along grain boundaries which made this quite a dubious item from the start (Figure 1).
The analyses at SSEF confirmed that this ring is a heavily treated jadeite of rather poor quality (many fissures). The jadeite had been first bleached with acids and subsequently impregnated with artificial resin (polymer) and additionally dyed artificially to create the green colour. Chemical analyses showed a rather pure jadeite composition with minor amounts of iron (0.7 wt% Fe2O3) but nearly no chromium (only 0.003 wt% Cr2O3). The absorption spectrum is distinctly different to chromium-bearing jadeite. It is dominated by three broad bands at about 430, 600 and 675 nm mainly resulting from the green dye, with additionally a small peak at 435 nm from Fe3+ (Figure 2).