Which of the following describes fracture filling?

• A. Fracture filling is injecting a molten glass substance into surface-reaching feathers or laser drill-holes
• B. Fracture filling involves coating with resin on the surface
• C. Fracture filling removes feathers
• D. Fracture filling is an optical illusion

Answer: (A)

Fracture filling is a treatment that improves a diamond’s apparent clarity by filling surface-reaching fractures with a molten glass-like substance. The filler is injected into cracks such as feathers or laser drill holes and then hardens, reducing light leakage and making the fracture lines less visible. This matches the description that fracture filling involves introducing a molten glass substance into surface-reaching feathers or laser drill-holes. It’s a real treatment, not merely a surface coating or an optical illusion, and it targets the cracks themselves rather than removing them.