[205guy]

I came to say the same thing. The article hints that such a use is possible, but makes it sound like it is a modern discovery of its capabilities. Turns out that poisoning was always an effective way of killing enemies (even still today), and there are many tales of goblets or gems that could detect or (as an embellishment) purify a poison. The fact that such a goblet actually existed is the real story here.

I'm very surprised no historian is grabbing this research opportunity to see what salts, oils, etc. (based on historically known poisons) and what concentrations the goblet can reveal.