Distinguishing Authentic Amber from Reconstructed Amber
In the world of gemmology and paleontology, identifying the origin and quality of amber specimens is crucial. Amber, a fossilised tree resin, can be either natural or reconstructed. The Journal of Gemmology published an article in 2016 by Haibo Li, Jie Liang, Taijin Lu, Jun Zhang, and Jun Zhou, titled 'Identification of Reconstructed Amber from Different Periods', shedding light on the differences between natural and reconstructed amber.
Reconstructed amber is created by heating and pressing small amber fragments or scraps, often from Baltic material. This process changes the refractive index (RI) and infrared spectral readings of amber. Two main types of reconstructed amber exist: Type 1, without added substances, and Type 2, containing foreign substances.
The boundaries between fragments in early reconstructed amber have oxidised edges that appear translucent brown or red. In contrast, heat-enhanced amber displays brownish red flow lines that do not interconnect. Early reconstructed amber, made under high temperature and pressure conditions in air, is relatively easy to identify. It displays a dark body colour, poor transparency, a muddy-looking interior, and a diagnostic fragmental or mosaic structure.
Current reconstructed amber, on the other hand, is manufactured under higher temperature and pressure in an oxygen-free environment. The higher the temperature used in heating, the higher the RI will be, up to a maximum of 1.60. Viewed with a strong transmitted light source, opaque current reconstructed amber beads exhibit no 'blood streak' structure. However, the presence of small grains with angular boundaries is the key identification factor for current reconstructed amber. Current reconstructed amber usually shows a more subtle and fine-grained fragmental structure.
The identification of newer amber material presents a challenge for gemmological laboratories, as current reconstructed amber is often subjected to post-processing treatments that conceal identifying features. The most effective method to identify reconstructed amber from natural amber is microscopy, to observe the internal microstructure.
Natural amber, on the other hand, is fossilised tree resin that has undergone polymerization and hardening over millions of years. Its microstructure commonly exhibits inclusions such as trapped air bubbles, insects, plant debris, and microfractures that are naturally formed during fossilization. A relatively homogeneous polymer network is formed slowly through natural diagenesis, and internal stresses and natural cracks arise from geological processes and aging.
In contrast, reconstructed amber shows signs of artificial bonding or fusion, such as visible seams, uneven polymer networks, or resin-filled cracks. It may contain foreign substances or synthetic polymers that differ chemically and structurally from natural amber’s original polymer. The internal texture could be less homogeneous, sometimes showing layering or "patches" where fragments were joined.
To distinguish early and currently reconstructed amber from natural amber, one should consider several key points related to their formation, physical properties, and microscopic features. By understanding these differences, gemmologists and paleontologists can authenticate the origin and quality of amber specimens accurately.
- Gemmology workshops and courses can include instruction on identifying the differences between natural and reconstructed amber, such as understanding the origin of these materials and their characteristics.
- In the scientific world of gemmology and medical-conditions, reconstructed amber, Type 1 and Type 2, are of interest due to their unique properties, especially their modified refractive index and infrared spectral readings.
- Technology plays a vital role in identifying reconstructed amber, as higher temperatures used during its manufacturing process can be detected through microscopic examination, revealing signs like angular grains and opaque bead structures.
- Networking within the gemmology community is essential for collaborative research on amber, enabling professionals to share knowledge and advancements in testing methods for identifying the origin and quality of amber specimens, particularly in light of advances in technology and treatment processes.
