This chart, developed by Peter over many years, is a template for the therapeutic application of the gems. On one axis of the chart, he has placed the element of crystal structure, which describes eight specific personality types or ‘psycho-emotional forms’. Peter elucidates these ‘essential trends of thinking and feeling’ in his book ‘Psyche and Structure’.

On the other axis he uses the quality of colour affinity, which he attributes to mental, physical and spiritual indications.
In assessing and combining these qualities and forms, the practitioner is guided to a group of crystals, which have an affinity to the situation or condition at hand.

The chart can be used as a foundation to select a gem essence, to take the homœopathic preparation of a gem or to wear the gem itself.