Thirty carats. The chemical name of Mosang Petrochemical Company is synthetic silicon carbide, and its composition is almost colorless, with refractive index of 2.56-2.69, dispersion of 0. 104, birefringence of 0.043, hardness of 9.25 and density of 3.22g/cm3. According to the density shape, 20mm mosan stone is about 30 carats, and the 20mm mosan stone of Linxia Zhubao on sale is also about 30 carats.