This also resembles turquoise and is light green
to greenish blue in color with a distinctive mottling and grid like
pattern not seen in turquoise. It also has a refractive index of 1.52
to 1.53, much lower than that of turquoise, and shows an uneven or splintery
fracture as opposed to the conchoidal or granular fracture of turquoise.
It often has a veined or mottled appearance with
a yellowish-brown matrix, a close enough resemblance to have earned
the misnomers of Nevada or Californian turquoise. However, its refractive
reading of 1.56 to 1.59 is much lower than that of turquoise and it
will appear pinkish when viewed through a color filter, whereas turquoise
shows no color change through a filter. Variscites color should be a
deterrent in itself, as it resembles that of only poor-quality turquoise.
This is a naturally opaque white stone with a dark,
spiderweb matrix appearance, similar to that of turquoise and therefore
commonly dyed to imitate the more expensive stone. A quick and easy
test to separate the two is a color filter; viewed through a filter,
dyed howlite will appear pink or red. Howlite also has the lower refractive
index of 1.58 to 1.60 to that of turquoise. As a third test, albeit
a destructive one, a drop of hydrochloric acid on an obscure spot on
dyed howlite will attack the stone and leave a distinct dull spot.
Synthetic Turquoise is virtually identical to natural
turquoise but will show artificial-looking matrix as well as a distinctive
darker blue, spotty appearance on a lighter background, visible fewer
than 30 to 50x magnification. This appearance is better known as the
'cream of wheat' effect and is a dead give-away.
These will show a vitreous luster on small fractures
as opposed to the waxy luster of the natural stone. Glass and plastic
imitations will show signs of tiny bubbles under magnification. Touching
plastic imitation turquoise with a hot point will melt the surface and
emit an acrid odor. Another practice, one that can trace its origins
back to 2000 B.C., is that of reconstituted turquoise. Known as faience
during the Egyptian period, the material consisted of a quartz paste
that was shaped, glazed, and fired to resemble sky-blue turquoise. Today,
reconstituted turquoise consists of pulverized turquoise rock, mixed
with resin and injected into a mold to form a solid brick, which is
then shaped. Pulverized pyrite is sometimes added to better imitate
So, What to Do?
Don't despair, though. The best solution is to buy
your turquoise from a reputable dealer who won't hesitate to discuss
treatments with you and supply you with a written guarantee that your
purchase is nothing else but natural turquoise. Always purchase your
turquoise jewelry from a reliable jeweler.