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Zircon virsus cubic zirconia


#1

How do I explain the difference to someone who between zircon and
cubic zirconia? Anne


#2

Unfortunately many, many people confuse these two. The two are
described below in somewhat technical terms. Simply, CZ is a
synthetic chemical which is used to simulate diamond. Zircon is a
natural mineral which is cut into gemstones and is usually clear and
highly reflective, and also is used to simulate diamond.

John


#3
How do I explain the difference to someone who between zircon and
cubic zirconia? Anne 

The two materials are totally different materials. Different
chemical formula, different crystal systems, different optics and
durability, and more. The similarity in their names is the main
confusion. Their common ground is that both contain the element
zirconium in their formula, and that when white, zircon has been used
as a diamond substitute (as have most other colorless stones). Zircon
shares with cubic zirconia a high refractive index and dispersion so
it’s a good looking diamond substitute, but it is much softer and
more fragile than CZ. It is a natural stone, while cubic zirconia is
synthetic. Zircon is doubly refractive, while CZ is not (like all
cubic system minerals). Because of the very high double refraction in
many zircons, with a loupe you easily see a doubled image of back
facet edges, so even without the loupe, zircons often look “fuzzy”.

Both materials are interesting in their own ways. Cubic zirconia,
for example, was the first synthetic diamond simulant (looks like
diamond but is otherwise not related) that not only looked good, but
was also hard and durable enough to actually hold up reasonably well
in jewelry. Prior substitutes for diamond either didn’t look much
like it, or were usually quite soft and fragile gems (including
zircon).

Zircon, by contrast, is a natural mineral, not synthetic. One
interesting fact is that when originally formed, it usually contains
traces of uranium, which decays over long periods of time. That decay
is at a highly predictable rate, and can be used to measure the age
of a zircon crystal. Since zircons form in igneous rocks, they can be
used to measure the age of rocks they occur in, and this ability to
date zircons is useful because it covers a vast time scale, into the
billions of years. When some science show mentions that geologists
have found rocks that have been dated to be as old or older than the
earth itself, or similar sorts of time scales, it’s usually done by
analyzing tiny zircon crystals found in the rocks… That radioactive
decay (don’t worry, the stones are safe to wear. this decay takes
place over geologic time, so there isn’t a concern for radioactivity)
also has another interesting effect. Notice in my first paragraph
where I say “many” zircons have a high double refraction? It’s not
all of them. The older they are, generally, the lower that double
refraction. The reason is that the slow radioactive decay of the
uranium causes, over long periods of time damage to the crystal
structure of the stone, so that zircons have a whole range of optical
propeties from “high” to “low” zircons, with “high” zircons being
younger, with all that double refraction, and “low” zircons no longer
showing that so much…

It’s also useful to note that as with many natural gems, zircons
come in a number of colors. White is commonly known for it’s use as a
diamond susbstitute, especially in antique jewelry, but zircons also
come in attractive blues, yellows, browns, and all can be very bright
and attractive gems due to the high refractive index.

Peter Rowe


#4

Zircon is a naturally occurring mineral, with a very high refractive
index. Because of this, man thought it would makea great diamond
simulant. So, man created a synthetic zircon called cubic zirconia
(colorless or not) to simulate diamond.

Carol ackerman, G.G.


#5
How do I explain the difference to someone who between zircon and
cubic zirconia? 

Just tell them that CZ is a man made (or synthetic" stone, whereas
zircon is a natural stone which is mined. Also the two are chemically
different. I’ve never had anyone ask for further explanation, but if
someone does, breakout one of your gem reference books. Webster’s
"GEMS, their sources, descriptions and identification" is perfect for
that. If you don’t have one, andyou’re selling gems or gem set
jewelry, you really should get one.

Jerry in Kodiak


#6

Zircon is a natural stone. Cubic Zirconium is manmade.

Linda Kaye-Moses


#7
It's also useful to note that as with many natural gems, zircons
come in a number of colors. White is commonly known for it's use
as a diamond susbstitute, especially in antique jewelry, but
zircons also come in attractive blues, yellows, browns, and all can
be very bright and attractive gems due to the high refractive
index. 

Peter did a wonderful job describing natural zircon. I simply want to
highlight few things.

Natural zircon is a mineral with very simple composition. It is a
combination of zirconium oxide and silicon oxide. There are no
chromophores like in corundum for example. So what gives zircon all
the various colors ? It is the radioactivity that Peter was talking
about. A more gemological terminology would be color centers. If not
the radioactivity, all zircons would be colorless.

It is also worthy to mention that alpha zircons ( high zircon ) has
hardness of 7.5 on Mohs scale, while gamma zircon, also known as
metamict, is barely approaching 6. Metamict zircons are subjected to
prolong annealing and that restores their crystal structure, but it
is also makes them more fragile. Majority of zircon on the market is
annealed metamict.

Contrary to what Peter said, zircon can be dangerous. This needs to
be qualified. Radioactive inclusions in zircon primarily emit alpha
radiation. Alpha radiation cannot penetrate human skin, so wearers
are generally safe, unless there are cuts, open wounds, and etc.
Gemstone cutters are another matter. Alpha irradiated material when
inhaled, is dangerous. One should not confuse alpha zircons which are
not radioactive with metamict zircons, which are alpha radioactive. I
guess that is why terminology of high and low was adopted.

Annealed zircons remain radioactive, but since their birefringence
is restored, it can be difficult to tell them apart. One way is to
look for pleochroic halos which are the signs of radioactive damage
to the crystal structure.

Leonid Surpin
www.studioarete.com


#8

Peter Rowe was very complete in reply to the issue of what the
difference between the two are.

To recap:

Cubic Zirconia is a man made stone intended to imitate diamond or
other gems (they make colored ones too).

Zircon is a natural gem mined from the earth and is best appreciated
for its own beauty. It has been used in its colorless form to
imitate diamond but it is worth noting that it is almost never mined
as a colorless mineral. This clear “color” (or lack thereof) is
almost always due to heating which leaches out the original color of
the gem which is usually red, brown, orange, yellow, purplish, green
or some combination of these colors. Almost all blue zircon are also
heated from a reddish brown color (this only works on stones from
certain mines, mostly from Cambodia) and the other colors are often
heated to get a little lighter and more saleable color. The lighter
colors show much better the incredible dispersion that Zircon has.

Hope this furthers the education of all!

John Dyer
www.johndyergems.com


#9

Hi Carol,

With all due respect, you are very mistaken. Cubic zirconia is
definitely NOT a synthetic zircon.

Different crystal systems, different chemistry…about the only
thing common to each is a similar name.

Wayne Emery
thelittlecameras.com


#10

For heavens sake just google the two. Zircon is a naturally
occurring silicate; zirconia a man made oxide. Entirely different
stones, different properties.

Cheers
Hans Durstling
Moncton, Canada


#11

I am wondering about the danger from irradiated zircons mentioned in
a previous post.

Is there really a danger to wearers if there is an open cut or
abrasion on their skin while wearing jewelry set with this type of
stone? If so, does this apply to other irradiated stones?
Thirty-three years making jewelry and I’m still learning new things
(almost every day)!

Thanks for on this,
Linda Kaye-Moses