Artificial Glass Imitating Blue Amber
Artificial glass, a low-cost material, is capable of simulating any gemstone owing to its range of appearances (bodycolor, transparency, and phenomena). While this material is usually straightforward to identify, in some cases it is visually similar to the gem material being imitated. The Lai Tai-An Gem Laboratory recently received an object for identification that the client claimed was blue amber, but was subsequently determined to be artificial glass (figure 1).
The transparent, irregularly shaped, brownish yellow object with a bluish surface-related effect and vitreous luster weighed 139.34 ct and measured 37.0 × 33.2 × 28.6 mm. While it closely resembled amber, its heft was completely at odds with that expected for an amber of its size, providing the first important clue about its identity. Standard gemological testing revealed a spot refractive index of 1.50, a specific gravity of approximately 2.50 (amber’s is 1.08), a weak chalky blue reaction under short-wave ultraviolet radiation, and an inert response to long-wave UV. Inspection with a gemological microscope revealed gas bubbles (figure 2). Standard gemological testing confirmed that the item was not amber but artificial glass, though more advanced analysis was carried out. Fourier-transform infrared (FTIR) spectrometry was consistent with data we obtained on some samples of known glass (figure 3), confirming the identity. Energy-dispersive X-ray fluorescence (EDXRF) spectrometry also detected Si and Pb as the main chemical elements.
Blue amber’s optical effect, produced by the extremely shallow blue fluorescence stimulated by UV light, is strictly confined to the surface. A strong blue fluorescence under long-wave UV radiation is also typical in such amber, so the inert reaction also indicated the material's artificial nature. The object exhibited a similar optical effect when viewed at different angles or when the direction of illumination changed.
In our experience, it is uncommon to see this type of artificial glass imitating blue amber. The gas bubble inclusions, while typical of glass, may also be encountered in amber, so additional gemological analysis may be necessary to ensure the correct identification. This case clearly illustrates how artificial glass can imitate virtually every gemstone imaginable and mislead the unwary bargain hunter.