The best test would be to have CarolC around for tea while one has one of these crystal thingies hidden in a cupboard. If she suddenly gets sick then there maybe something in what she says (or there may not be - other variables - coincidences in diet, climatic conditions, state of mind when these attacks occured - could well be taken into account). I would point out that CarolC having my fellow sceptics visit her with a crystal would not be a 'fair test', because as soon as she saw them she would be aware that a test was imminent. If her symptoms are a psychosomatic phenomenon as I suspect as a sceptic, this could trigger them off.