Porosity, blowholes, and sand holes are the most common surface defects in jewelry manufacturing, especially in precious metal vacuum casting, gypsum mold precision casting, and wax-set casting. Jewelry requires ultra-high surface finish and fine detail retention, so even small holes will damage appearance, reduce density, weaken mechanical strength, and cause cracking or stone loss in later processing. For high-value materials like gold, silver, platinum, these defects directly increase scrap rate and production c···...