French, Williams, O'Donnell and Davies (2001)
British Psychological Society Centenary Conference, Glasgow — conference paper, not a peer-reviewed article · 80 volunteers
Tested Whether meditating with a real quartz crystal produces effects a visually indistinguishable fake does not
Found Participants reported the expected tingling, warmth and concentration effects at the same rate with fake stones as with real ones. Reported effects tracked prior belief in crystal power, not the stone.
Since The design has not been formally replicated; its result is consistent with the wider placebo literature





