Test it how? I just assume it is all dyed & stabilized (and tell my customers that), but it would be great to be sure. Without destroying the turquoise, of course.
There are several easy to do methods to test if turquoise is
stabilized with plastic resin. The easiest is of course the rough
stone. You will be able to see plastic resin in nooks and crannies of
the stone.
If you have a cab that is not set in jewelry then you can do the hot
needle test. Heat a needle or paper clip until it’s red hot then lay
it across the back of the cab. It the smoke smells like plastic then
it’s stabilized.
If the stone is already set in jewelry then you can rub the stone
rapidly against you pant leg, jeans are required for this test, until
the stone is heated up by the friction then hold the stone close to
your nose and you should be able to detect a plastic smell if
stabilized with plastic resin.
Turquoise that is stabilized by silication is almost impossible to
detect without sending a sample to a lab for analysis and even then
there are certain stabilization methods that are undetectable.
Dyed stone or colorshot material can usually be detected by close
inspection with a loupe. When buying turquoise beads buy a test
strand first then break a couple beads and look if the inside shows
white. That will indicate dyed howlite or magnesite. Usually the
color will look splotchy if dyed when areas of the stone absorb the
dye at different rates.
Buying turquoise is definitely a buyer beware situation. There are
known scam artists all over the southwest US selling stabilized
stone for gem quality turquoise from certain mines that turquoise has
a high value. I know of one case where a seller knowingly sold dyed
howlite as gem turquoise. The case is in the hands of the New Mexico
state attorneys. Mix in turquoise coming from around the world and
it gets even worse. I talked with a big bead dealer from Gallup, NM
and he told me he has to go to China twice a year to make sure he is
getting exactly what he is paying for. Many of the Chinese bead
manufacturers use turquoise and howlite as synonymous terms. In
other words, “Sure we have turquoise. What color would you like it?”
Rick Copeland
Rockymountainwonders.com