Glossary term
Fracture filling
Filling surface-reaching fissures with glass or resin to improve apparent clarity.
Fracture filling introduces a substance, commonly high-lead glass in corundum, into surface-reaching fissures to make them less visible. Filled stones need careful handling (heat, acids and even ultrasonic cleaning can damage the filler) and are valued far below untreated material. Disclosure is mandatory under international trade standards.