he grading and evaluation standards of rubies are mainly based on 1T and 4C: Průhlednost, Barva, Jasnost, Střih, and Carat. 1. Průhlednost: refers to the degree to which a gemstone allows visible light to pass through. In the visual identification of rubies, transparency is generally divided into five levels: průhledný, průsvitný, průsvitný, podprůsvitný, and opaque. […]
