In current usage, "natural turquoise" is used in two ways.
First, the phrase is used to describe turquoise that has not been treated in any
way with dyes, stabilizing epoxies, or other chemical treatments intended to
alter the color, hardness or luster of the stone. Natural turquoise cannot
be easily found in the marketplace. The purist who seeks it is advised to
buy direct from the mine. It has been claimed that as little as 3-10
percent of turquoise mined is of sufficient hardness to be used in jewelry
without stabilization. Natural turquoise is rare, indeed.
The term has also been used to describe turquoise that has not
been treated with dyes or epoxies, but has been given a wax or oil coating for
protection. Since the porosity of turquoise can lead to discoloring,
staining and dehydration, only the most conservative purist would object to wax coatings.
"Natural Processed Turquoise"
"Natural processed" seems like an oxymoron to us, but the phrase
is now starting to appear in the marketplace. This is a proprietary
method, so we know very little about it. Apparently, turquoise is
soaked in nontoxic chemicals to increase luster and color. The method is
also claimed to leave no physical evidence of alteration. One advantage is
that turquoise subjected to this secret treatment is less likely to turn green