Plastic Treated Emeralds

(via ICA Lab Alert No. 6, August 13, 1987) Nubio Horiuchi writes:

Source
I have personally seen this treatment for the past three years in Japan (Central Gem Laboratory).

Status
Details of this have not been announced yet, but it is summarized as follows:
The fractures are first cleaned and then impregnated with some kind of liquid plastic. It is presumed that the liquid plastic is hardened by irradiation of light or ultraviolet rays.

Merit of this treatment
In normal oil treatment the oil will seep out during cleaning or over a period of normal wearing and there is a gradual loss of color and the fractures become noticeable. However, with the impregnation of liquid plastic the treatment is durable.It would appear from the durability standpoint that the liquid plastic treatment is better than oiling.

Identification
It is difficult to distinguish between oil and plastic treatments.

Question
In which category of enhancement and treatment should the plastic treated emeralds be classified?

E. Gubelin writes:
Though more durable the result of this new plastic treatment should become to known to all members immediately, because many members of the trade use an ultrasonic cleaning machine which causes the oil to be washed out. If no oil is being washed out, people might not become aware of the fact that the fractures are filled with plastic films. Despite the greater durability the stimulus for easier fraudulent practices does by no ways raise the ethical standard of this plastic treatment.

Dr K Schmetzer writes:
The stones should be classified as plastic-impregnated emeralds.