Treatments of gemstones has been done since
the beginning of the trade. And emeralds are not exceptions. Heat treatment is
NOT performed on emeralds (like rubies, sapphire, aquamarine, tanzanites,
amethysts, tourmaline), but it is oiling the accepted treatment, either with
or epoxy resins. It is estimated that 99% of all emeralds are oiled or resins
treated. This has the effect of reducing the visibility of the
inclusions, and improving the clarity of the stone.
Cedar wood oil: