Natural sapphires often contain inclusions. During the cutting process, these inclusions are removed from the rough stone to create a gemstone with minimal inclusions. However, some inclusions may still be present. To assess them, you can apply a thin layer of oil to the gemstone and examine it by torch. This method reveals any remaining inclusions, allowing you to determine if the gemstone is ‘eye clean’—meaning it appears free of visible flaws to the naked eye.
