การประชุมวิชาการระดับชาติ ครั้งที่ 16
มหาวิทยาลัยราชภัฏนครปฐม

The aims of this research to develop artificial Hauyne gemstones from glass materials using rice husk ashes in Suphanburi Province. Glass was prepared from the formula (55-x)SiO₂: 13B₂O₃: 20Na₂O: 6.3CaO: 0.2Sb₂O₃: 1Al₂O₃: 4.5BaO: xCoO mol% where x is the concentration of CoO (0.00, 0.01, 0.02, 0.03, 0.04 and 0.05 mol%) have been synthesized by conventional melt quenching technique at 1,200 ^oC for 3 hours. Studied the physical properties and the optical properties of glass The results showed that density and refractive index tends to increase according to the increasing concentration of Cr₂O₃. The molar volume decreases with increasing concentration of Cr₂O₃. The absorption spectra of glass in the wavelength range of 200 to 1,100 nm showed absorption broadbands at 539, 597 and 643 nm, caused by the energy level change from ⁴T_1g (F) → ²T_1g(H), ⁴A₂ (⁴F) → ⁴T₁(⁴P) and ²T₂ → ²T, respectively. Color analysis of the glass sample revealed that the a* value ranged from -1.27 to -2.45, while the b* value ranged from -54.56 to 2.78, falling within the blue color spectrum. It was found that glass doped with CoO at 0.04 mol% had L* = 52.36, a* = -10.1118, and b* = 24.7183. The color value was close to that of real Hauyne in nature and have similar physical characteristics.