I do have another question about turquoise though.
Turquoise goes green over time and I'm wondering if there's
some solution that could reverse the oxidation , if thats whats
turning it green? Or could you even put green turquoise in hot
pickle and would that strip the green away?
I have worked with turquoise for close to 25 years, having
started my career in the Indian goods trade. Allow me to get on
Most turquoise is fairly soft, with the better turquoise in the
range of Mohs hardness of 5-6. Some turquoise is extremely hard,
with a Mohs of 7.0-7.5, but it is very rare and quite expensive.
Stabilized turquoise is so soft, it has been “stabilized” by
injecting resin under pressure to make it hard enough to take
cutting and polishing. Turquoise is a compound of hydrous
phosphate of copper and aluminum, and occasionally iron. This is
why turquoise is usually found in copper mines.
Stabilized turquoise will not change color with time because the
resin prevents absorbtion of most chemicals, e.g. chemically
inert. Enhanced turquoise has had the color improved by inducing
an electrical charge, sometimes with heat also. Gem grade
turquoise is hard and low in porosity, and will not change color
over time under normal wearing conditions. Natural turquoise will
change color over time, due to normal environmental factors, and
will aquire a “patina”. This patina may range in color from a
deep royal blue to a deep sea-green. It is much sought after by
turquoise afficianados. The reason for the color change is
because natural turquoise is somewhat soft, it is able to absorb
perspiration and oils from a person’s skin. Depending on the
wearer’s pH, the color will be more blue or more green over time.
Likewise, because it is porous, it can also absorb things such
as lotions, dishsoap, cleaning agents, alcohol and all the other
lovely things we women use on a regular basis. These can be
absorbed into the turquoise with detrimental color changes.
Ammonia will change turquoise to black over time. Most jewelry
cleaning solutions have some type of ammonia.
Jewelry with turquoise in it should never be cleaned with any
commercial type of jewelry cleaner. The best way to clean this
jewelry is the old-fashioned way, with a buffing compound (I use
Fabulustre) or something like a Sunshine Cloth. Buffing compounds
need to be removed with plain water and a toothbrush, or using a
When we bought turquoise jewelry, we had to determine whether it
was natural, stabilized, oiled/waxed or enhanced. Most times we
were able to determine by feel, although it took a lot of
training. Oiled/waxed turquoise has a greasy drag to it,
stabilized is slick and glassy, natural and enhanced are slick
with a slight drag. If we had a problem determining if a method
was used, we would go to the oxalic acid and hot pick methods.
Oxalic acid will leave a white spot on the turquoise if enhanced,
with no effect on natural turquoise. A red-hot needle will give
off acrid fumes if stabilized, and a smoky wisp if waxed or
oiled. Natural turquoise will just smell like hot rock. Another
method was to drag the turquoise across our tongues, but we had
to stop that when we had a hepatitis pandemic.
Today, however, none of these methods are absolutely reliable.
Turquoise may be both enhanced and stabilized and the oxalic acid
won’t be a sure clue. Fracture sealing is also listed under
stabilization methods, so it only shows up in the areas that were
porous enough to absorb the resin. Most people have no clue if
their turquoise has been treated in some way. So it’s best to
play it safe when cleaning this jewelry, and charge more for the
Other soft stones, such as lapis, coral, shells, malachite and
others with a Mohs hardness of less than 7.0 can be adversely
affected by commercial cleaning solutions.