"Only the highest quality gemstones are truly healing. Gemstones of lesser quality have significantly less, if any, therapeutic effect—and, indeed, can even have a detrimental effect on their users. Only therapeutic-quality gemstones allow the full range of a gemstone’s healing properties to be expressed, and they alone should be used for the purposes and benefits the Gemstone Guardians describe."

Therapeutic-quality gemstones are those which meet the high standards for physical purity and quality set by the Gemstone Guardians. For every gemstone there is a different set of criteria which makes that gem therapeutic.

"An infinite number of gradations exist between gemstones whose physical nature is so pure that they can express their energies freely and gemstones so choked by inferior color, poor clarity, and contaminants that their energies are trapped, corrupted, or nonexistent....

Where is the line that separates therapeutic quality from that which is unacceptable? To be therapeutic, a gemstone's physical matrix must be virtually free of foreign matter. [It] must also exhibit all its own unique parameters for therapeutic quality, and these parameters must be present in proper proportion. Anything less may distort the character of the gemstone's energy and make that gemstone unsuitable for medicinal purposes."