Observe the content. Natural amber sometimes contains insects, plant branches and leaves, minerals (such as calcite in Burmese amber) and so on. Insects in imitations are mostly killed first and then embedded; It is easy to distinguish from the insect morphology in natural products.
Whether there are turtle cracks on the surface, generally, old amber is oxidized due to contact with air, resulting in turtle cracks, and the honey juice is relatively uniform and delicate; The imitation turtle cracks are thick and few, which is obviously different.
Whether the color is natural and whether there is artificial coloring; The color of dyed amber (red, blue and green) is unnatural, and dye distribution can be seen in microcracks.
Artificial heat-treated amber (put in oil or heated in sand to improve transparency) generally has disc-shaped and leaf-shaped cracks (water lily leaves) (photos), which is very common in the currently popular Baltic amber pendants with any shape. According to the national standard, heat treatment belongs to "optimization", and the name column in the test report can be omitted; But it should be explained in the enlarged inspection column of the test report.
Through hot pressing, small pieces are polymerized into larger pieces, which belong to "recycled amber" (according to national standards, it must be indicated). Impurity residues are often seen at the junction of original fragments in recycled amber.
2. Refractive index measurement: The refractive index of amber is relatively fixed, about 1. 540 。 The results of refractive index measurement are helpful to objectively distinguish amber from imitation amber.
3. Density measurement: jewelry testing laboratories generally use precision balance to measure amber with distilled water according to Archimedes principle (hydrostatic method). After temperature measurement correction, the obtained density value, combined with refractive index and other data, can accurately distinguish amber from non-amber.
Some merchants use saturated saline (50 ml of water and 7 g of salt, the density is 1. 19g/Cm3): the density of amber is 1. 05—— 1。 10 g/Cm3, floating on saturated salt water; The amber content of mineral inclusions can be as high as 1. 3, so it will sink; General merchants rarely use this method to judge, only for amateur buyers. In the experiment, plastics, celluloid (cellulose acetate) and bakelite all sank; Polystyrene will float, but the refractive index is 1. 59, measuring a refractive index can be simply resolved. After the salt water test, rinse with clear water and dry with a soft cloth. Bakelite, also known as bakelite in the west, is called Leo Hendrick Backlander. He invented bakelite in 1909.
4. Ultraviolet fluorescence experiment: amber of different colors is blue-white fluorescence under long-wave and short-wave ultraviolet fluorescence; Weak transparency and strong opacity. But some dark amber has no fluorescence. The fluorescence of ordinary plastic imitations is very different from that of amber.
5. Needle burning method: the needle is heated to red, and the smoke generated by scalding the amber surface in an inconspicuous place (such as a perforated wall) is black and fragrant, and the burnt place is gray. Plastic imitations are pungent in smoke, blue or white in color, which will melt in scalded places and bring out silk when pulling out needles. Celluloid smells like mothballs.
6, finger friction method: if amber will have a loose fragrance.