As-grown and facetted crystals of the synthetic hydrothermal emeralds imported from USA and USSR were examined on their morphologies, surface and internal features and physical properties. Their characteristics, growth conditions and seeding techniques were compared to each other. As seen in the following summary, the USSR emeralds are much closer to natural emeralds in their propertes, as compared to the USA emeralds. Only the internal features will provide with evidences to distinguish the USSR hydrothermal emeralds from natural emeralds. (USA) SG : 2.67〜2.68 ; H : 7.5〜8, ω : 1.572〜1.574, ε : 1.568〜1.569, ω-ε : 0.004〜0.005 ; O : yellowish green, with absorptions>7200Å(m) 6810A(m) 6790Å(s) 6340〜6370Å(s) 5700〜6160Å(s) 4760Å(m) <4700Å(m) ; E : bluish green wlth absorptlons > 7200Å(m) 6780〜6800A(s) 6570〜6620Å(m) 6380〜6490Å(s) 6250Å(w) 5800〜6160Å(s) 4760Å(w) <4550Å(w) ; IR absorption : 3690cm<-1>(s) single ; UV-fluorescences : 2573Å dull red, 3650Å bright red ; colour through Chelsea filter : red ; internal features : optical strains and micro-textures of various types, cracks of various types including the earthworm track-type, zonal structure along seed plate ; inclusions : gas-liquid 2 phases, phenacite, spikes, dark brown materials, occasionally 3 phases inclusions in seed-plates of natural beryls ; seed-plate : occasionally natural beryls cut angle 35〜37° to c-axis ; growth plane : mainly (112^^-1) ; estimated growth time : l〜3 months ; available depth of facetted stones : 6 mm with seed-plate, 3〜4 mm without seed-plate, degree of similarity to natural emeralds : 80, estimated from the above and the other data, normalizing natural emeralds as 100, for comparison 40〜60 for flux-grown emeralds. (USSR) SG : 2.70〜2.71 ; H : 7±〜7. 5, softer than the USA emeralds, ω : 1.583〜1.586, ε : 1. 577〜1.579, ω-ε : 0.006〜0.007 ; O : yellowish green, with absorptions >6900Å(s) 6770〜6800Å(s) 6340〜6350Å(m) 5760〜6080Å(w) 4760Å(w) <4700(s) ; E : bluish green with absorptions >6960Å(m) 6800〜6810Å(s) 6590〜6630Å(m) 6380〜6510Å(m) 6280Å(w) 6020〜6080Å(w) 5870〜5950Å(w) <4500Å(s), more pleochroic than the USA emeralds ; IR absorption : 3695cm<-1>(s) 3655<-1>(w) 3590<-1>(m), the same as natural emeralds ; UV-fluorescences : 2537Å none, 3650Å none〜partly dark red ; colour through Chelsea filter : none to dark orange-yellow, dull red near seed-plate ; internal features : weaker optical strains and micro-textures of various types with wheat-head texture, cracks of various types including the parting parallel to one face of {101^^-0} ; zonal structure : rarer than the USA emeralds ; inclusions : gas-liquid 2 phases, gas-liquid-solid (black coloured) 3 phases, dark brown materials, reddish brown platy-crystals, occasionally 2 or 3 phases inclusions in seed plates, lacking spike, phanacite rare ; seed plate : occaronally natural beryls cut angle 24〜30° to c-axis ; growth planes : mainly (112^^-1) and (112^^-0) ; estimated growth time : 1〜2 months ; available depth of facetted stones : 9 mm with seed-plate, 4 mm without seed-plate ; degree of similarity to natural emeralds : 90.
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