Treated Green Amber
In the summer of 2007, the AGTA GTC received some beads that were sold as green amber. We did extensive research on these beads and could not confirm natural amber at this stage. Not only did the properties not match these of natural amber, they also did not match those of any known amber imitation.
Normally, natural amber gives off aromatic fumes when heated. The fumes from the tested samples were not quite as aromatic as we would expect for natural amber. In addition, the samples were not easily attacked by chloroform or ether, and on top of that, there were some peaks missing in the FTIR spectrum. However, the FTIR spectrum was completely different than all known plastics.
Our client generously gave us the contact address from his supplier, Mr. Mueller of Facett Art in Idar-Oberstein. After a first contact, we received additional amber pieces in all different stages and could see some of the amber peaks get weaker at the same rate the amber got greener.
Going a bit more into the details, Facett Art let us know that they have taken some old patents and refined them (Figure 1).
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| Figure 1. Some of the old patents that can be found about the heat treatment of amber. Photo: Lore Kiefert/AGTA GTC. |
This involves a heating process utilizing an autoclave, but not all amber is suitable for treatment. This company uses amber from the Ukraine, near the area of Kaliningrad. At one of the satellite shows in Tucson, a Chinese company is also selling green amber, supposedly derived from South American amber.
At the end of 2007, I had the opportunity to visit the company Facett Art in Idar-Oberstein. Mr. Mueller showed me around, including his faceting facility (Figure 2) and described his treatment process.
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| Figure 2. Mr. Mueller is demonstrating the faceting of his green amber in his office in Idar-Oberstein. Photo: Lore Kiefert/AGTA GTC. |
In a two-step process, the amber is first heated moderately to see if any further treatment will result in the desired green color. Afterwards, the amber is re-heated in an autoclave using a higher temperature and some pressure. During the process, a dark brown viscous residue remains. After the second step in the heating process, the amber gets its clear green color (Figure 3), but only 20–30% of the samples can be changed like that.
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| Figure 3. A large drop-shaped green amber. Photo: Lore Kiefert/AGTA GTC. |
In the big piece (Figure 4), there is still some milkiness in the center. One possible explanation for the modified amber properties is the following: The "amber acid" is the volatile component of the amber that gives it the smoke and the smell and probably the peaks that were missing in the infrared spectrum. This component is "pressed" out of the amber using temperature and pressure. What remains behind are the more stable parts of the amber.
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| Figure 4. This large piece of yellowish green amber still shows some cloudiness in the center, demonstrating that the heating process did not completely affect the whole piece. Photo: Lore Kiefert/AGTA GTC. |
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| Figure 5. Treated green amber. Photo: Lore Kiefert/AGTA GTC. |
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| Figure 6. Treated green amber. Photo: Lore Kiefert/AGTA GTC. |
