Emeralds, by their very nature, often contain fissures and surface reaching cracks. To improve their appearance and stability, a common practice involves the introduction of oil or other substances into these imperfections. This process enhances the gem’s clarity and overall visual appeal by reducing the visibility of these inclusions. Cedarwood oil, due to its refractive index being close to that of emerald, is frequently used. The application involves immersing the emerald in the oil under pressure or vacuum, allowing the oil to penetrate the fractures.
This enhancement is significant because it allows more emeralds to be commercially viable. Untreated emeralds of gem quality are rare and command considerably higher prices. The practice also helps to protect the stone from further damage, as the oil acts as a buffer, preventing the propagation of existing cracks. Historically, various substances have been used for this purpose, dating back centuries. Modern techniques have refined the process, using more stable and long-lasting oils.
