What Does It Mean When A Stone Is Filled?
Cavities and fractures within the stone can compromise a sapphire’s clarity. Today many gems have been heated and infused with a chemical flux in order to improve their clarity, luster and durability. At high temperatures, the flux melts and penetrates surface reaching fractures or cavities in the stone. When cooled, the flux may either solidify into a glassy mass (fracture filling) or facilitate corundum re-crystallization within the fissure (flux healing). There is considerable debate in the industry about how much of the clarity enhancing effect is due to filling versus healing, but in either case, the treatment can make low value, poor quality sapphires more marketable.
Flux enhancements have also earned a bad reputation because in extreme circumstances poor quality gemstones are literally held together by the glassy filler. While this is not a widespread practice in the sapphire trade, this treatment is widely reported in the ruby trade. These glass or fracture-filled rubies can also be extremely fragile. Many are destroyed during the jewelry repair process, routine cleaning, or re-polishing. More treatments for enhancing sapphires have come out in the recent years, Diffusion Processes with Beryllium is one of these treatments.