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серебряные украшения оптом Китай акции Baolong: прозрачность и блеск драгоценных камней

The optical characteristics of gems refer to the special properties of gems when they absorb, reflect and refract visible light, as well as the interference and scattering of visible light in gems. Transparency is the ability of a gemstone to transmit visible light. It is usually divided into transparent, semi-transparent and opaque levels. Прозрачность: А […]