Hi, I have a customer who would like a clear CZ put in a ring to
replace a diamond. Are there different qualities of CZ or are they
all pretty much the same as long as the cut and proportion is good?
Thank You, Christine
Yes, there are a couple different grades of CZ’s. You probably want
what some suppliers refer to as “premium grade”.
David L. Huffman
Christine, Yes there are different qualities of CZ. I have cut from
rough stock many different qualities from many different
manufacturers. The best CZ is about double the price of the normal
CZ offered for sale. This CZ has no haziness in the stone and is
uniform in color.
Gerry Galarneau
As a practical matter, the only meaningful differences I have
observed in the several decades that I have been setting stones is
that the quality of cutting is the principal variable in C.Z.s. This
is especially evident in those stones that are sent out by a mass
mail merchandiser. Sometimes I get customers who have a handful of
these stones in their little plastic pouches. Most of them have poor
cutting. The ones to be especially careful about are the ones that
have knife-edge girdles. These stones are especially prone to
breakage. On the other hand…why care! C.Z. is dirt cheap. The only
real loss would be your time. In my opinion, the best use of C.Z.s is
as gifts to little children. They are great for playing “house” and
pretend. Ron at Mills Gem, Los Osos, CA.
I very rarely post to this board as I am primarily a lurker absorbing
all the good However, this post was one in which I felt
it necessary to write a response. I disagree with you totally on what
you said below and as a facetor that works with man-made materials I
was a little miffed at the thought that my work is only to be used to
"play house" and “pretend” as was put below. I am sorry that you feel
that way and it looks as if the only cut C.Z.'s that you have come
across have been the badly cut “mass marketed” stones. I hope that
you can find a good facetor that works in the material who can help
show you that using some of the man-made materials can unlock the
creative potential of faceting, when you don’t have to worry about
cleavage planes, brittleness, heat sensitivity and the hundreds of
other problems that a facetor faces when working with natural
material, not to say that man-made material is perfect and free of
problems. The fact of the matter is that their are quite a lot of
badly cut stones out there whether they are man-made or “natural”. I
know of a number of “retail” chains of stores that sell faceted
stones, for a premium price, that are so horrible that I cringe even
at the thought of using them as a preform. This is not meant to be a
"flame" or to start an argument over natural vs. synthetic.
In response to the original question C.Z.'s vary in quality by the
method in which they are produced, also and most importantly some of
the different ways in which they are created need different techniques
in cutting. I think and this is my opinion that the hydrothermal
created material is of superior quality, but this may be just the
technique I use in faceting. Have you thought about using silver
topaz instead of C.Z. as a diamond substitue. If I remember correctly
silver topaz has a higher R.I. (Refractive Index) than C.Z. and this
may be a stretch but I think it is the same R.I. or maybe higher than
diamond. So if all you are looking for is a diamond substitute I
think silver topaz would be my first choice and not C.Z.
Here in frigid cold Indiana,
Terry
Terry: I am sorry to inform you that CZ is never made by the
hydrothermal process. It requires the “skull melt” method to produce
CZ. No other method can produce the high temperatures for the period
of time necessary. Also “silver” topaz does not have a higher R.I.
than CZ. I don’t know who is giving you this mis
Ed Katz, G.G.
I very rarely post to this board as I am primarily a lurker absorbing
all the good However, this post was one in which I felt
it necessary to write a response. I disagree with you totally on what
you said below and as a facetor that works with man-made materials I
was a little miffed at the thought that my work is only to be used to
"play house" and “pretend” as was put below. I am sorry that you feel
that way and it looks as if the only cut C.Z.'s that you have come
across have been the badly cut “mass marketed” stones. I hope that
you can find a good facetor that works in the material who can help
show you that using some of the man-made materials can unlock the
creative potential of faceting, when you don’t have to worry about
cleavage planes, brittleness, heat sensitivity and the hundreds of
other problems that a facetor faces when working with natural
material, not to say that man-made material is perfect and free of
problems. The fact of the matter is that their are quite a lot of
badly cut stones out there whether they are man-made or “natural”. I
know of a number of “retail” chains of stores that sell faceted
stones, for a premium price, that are so horrible that I cringe even
at the thought of using them as a preform. This is not meant to be a
"flame" or to start an argument over natural vs. synthetic.
In response to the original question C.Z.'s vary in quality by the
method in which they are produced, also and most importantly some of
the different ways in which they are created need different techniques
in cutting. I think and this is my opinion that the hydrothermal
created material is of superior quality, but this may be just the
technique I use in faceting. Have you thought about using silver
topaz instead of C.Z. as a diamond substitue. If I remember correctly
silver topaz has a higher R.I. (Refractive Index) than C.Z. and this
may be a stretch but I think it is the same R.I. or maybe higher than
diamond. So if all you are looking for is a diamond substitute I
think silver topaz would be my first choice and not C.Z.
Here in frigid cold Indiana,
Terry
Dear Terry, Sorry to have touched upon a sore spot with you. My
comments certainly weren’t intended to demean anybody’s choice of
cutting materials. Nonetheless, the material in which you invest your
labor and skills automatically demeans your efforts if it has little
or no intrinsic value. C.Z.s can be purchased in well cut stones for
as little as a dollar a carat…less in quantity. It usually takes
many hours for a cutter to produce a quality cut using modern
equipment. Foreign cutters can often cut much faster and just as well
using the jamb peg method ( this method actually takes much more
skill than using conventional modern equipment, but it takes a lot of
talent to be able to reach that level of skill. ) Commercial cutting
in various foreign venues can be had for approximately eighty cents
per carat. Cutting here in America usually starts at about
Twenty-five dollars for the first carat and somewhat less thereafter.
Assuming that you are cutting a one carat C.Z. it follows that you
should get twenty-five dollars for the stone and possibly more for a
very fancy stone. The value of the material is inconsequential. At
this rate you are probably earning somewhere between five and ten
dollars per hour. Suppose, on the other hand, that you are cutting
some nice Amethyst. In this case you are going to be able to charge
significantly for the value of the material along with a fair stipend
for your cutting. Your chance of being generously compensated for
your efforts increases by virtue of the fact that a profit can be
realized by upgrading the value of the rough. If you buy your rough
at a good price, your profit potential is potentially astronomical.
Yes, I am afraid that I would have to continue to suggest that C.Z.
,as well as most lab created stones, are definitely “pretend” gems. I
would never dream of denying their individual beauty, but they
certainly can’t be construed to be rare or precious. History has
taught us that mass production inevitably results in lower prices.
Without belaboring the issue, I recently had an interesting
experience which points out what I am talking about. Two ladies came
to me wanting custom mountings for their loose stones. One of the
stones was a ho-hum Citrine and the other was a terrible Ametrine.
Both of the stones were stunningly cut…perfect in every detail. I
mounted the Citrine as a pendant, but I suggested to the other lady
that she might not want to spend money on a mounting using a stone
with little or no value. Not only did the stone have the worst
possible color ( or lack thereof ) , there was a feather running from
girdle to girdle through one third of the diameter. The poor lady had
spent one hundred fifty dollars for a stone that had no intrinsic
value ! The moral of the story: you can’t make a silk purse out of a
sow’s ear…corny, but ever so true ! Ron at Mills Gem,
Los Osos, CA.
See what working third shift will do too you ;P. Anyway Silver Topaz
has an R.I. of 1.62 and CZ has an R.I. of 2.15-2.18. I was thinking
of synthetic rutile which has an R.I. of 2.61 to 2.90. Diamond has an
R.I. of 2.41. Also Strontium Titanate is a consideration as well it
has an R.I. of 2.41 which is the same as diamond and is considerably
cheaper than the synthetic rutile. Thanks to Lester for bringing that
to my attention 
Creative Gems sells most of the materials above. I
don’t know if they have cut stones as I don’t work for them just a
real happy customer over the years.
The cold freezing my brain in Indiana,
Terry
Hey Ron, I have to agree with all of your comments on CZ except one.
You actually CAN make a silk purse out of a sow’s ear. There is a
local high end consulting firm here called Arthur D. Little Co. who
like to prove how smart they are and they actually did make a silk
purse out of a sow’s ear. They also built a lead balloon that did fly.
PLEASE don’t ask me how they did these things as it is way outside of
my technical knowledge and the article I read about it ran quite a few
years ago. It just goes to show that you can’t judge a book by its
cover…no wait a minute they might have disproved that one too.
Daniel R. Spirer, G.G. Spirer Somes Jewelers 1794 Massachusetts Ave
Cambridge, MA 02140 617-491-6000 @spirersomes
www.spirersomes.com
For the record…
Topaz RI 1.61-1.62
CZ RI 2.14 - 2.20
Diamond RI 2.417
Topaz ios much, much lower - but I think it a wonderful “bright”
stone and use it a lot. The trouble with using it in a ring is that it
is easlily cleaved (it splits in two ) and it is also bi refractive -
you can see a doubling of the facets from the front.
Tony Konrath
Gold and Stone
www.goldandstone.com
tony@goldandstone.com