Primary Test: Magnification should be all you need. The dye used to impart an artificial color in emeralds is by nature a green color. Since the only way the dye process will work is by the emerald having small open fissures through which the dye can enter the stone, it is only logical to realize that the green dye will be visible somewhere in these fissures. And that is exactly what happens and how to identify this treatment as shown below.
Secondary Tests: None should be necessary.
Repair and Setting: Extreme caution with this material as any cleaning solution will most likely remove the dye compounds and cause the emerald to significantly lighten in color. Customer should be informed of the dyed nature of the stone before any repairs or resetting is initiated. No heat, no ultrasonic, and no cleaning solutions of any type.