B7000 glue. Although B6000 glue can also stick to gems, its viscosity is slightly lower than that of B7000 glue, and its hardness after drying is also worse than that of B7000 glue. B7000 glue has strong adhesion, water resistance, high temperature resistance, and can be firmly adhered to gemstones. After drying, the hardness is relatively high and it is not easy to break. In addition, the glue B7000 has certain elasticity, which can cushion the impact force when the gemstone is impacted or vibrated, and protect the gemstone from damage. Therefore, B7000 glue is recommended for hand-made precious gypsum.