Reference work entry
In mineralogical terms, feicui is a jadeite composed of microcrystalline aggregates of sodium aluminosilicate pyroxene. It is opaque or translucent with a Mohs hardness of 6.5–7 and a density of 3.25–3.4. Based on the green hue, brightness and saturation, jadeite can be divided into emerald green, apple green, shallot green, spinach green, oily green and greyish green. It is a precious gemstone and can be divided into grade A jade (all natural, without artificial colour), grade B jade (impurities have been removed through bleaching and filled with resin; it is subject to ageing, discolouring and cracking easily upon heating), grade C jade (dyed colour but no filler) and grade B + C jade (with filler and dyeing agents in cracks or grain pores). Tourists should be cautious in differentiating these types when purchasing jadeite (Fig. 2).
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