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Anyone been involved in making CZ?

As a new member, I’m delighted to participate and to try to link to other professioinals in our industry.

I work for a jewellery manufacturer, we often source CZ from various suppliers to fulfill our orders from wholesalers and retailers.

There’s been a growing trend of enquiries over especially the last 18 months from our customers wanting to know more about the environmental impact of them trading in jewellery, and so we have dug deep and looked into all aspects of our business processes so that we can give as accurate and open responses as possible to such enquiries.

It’s involved and takes time but certainly possible for us to assess and measure our own processes and to come up with statements concerning, for example, the consumption of electricity and other energy sources within our business.

However, things really slow down when we approach our suppliers for pertinent details of what’s involved, or consumed or wasted from their own processes - understandably they are mostly very adverse to letting out much detail at all.

Of particular interest to us at this time is the energy consumption associated with the manufacture of CZ and to date we have not been able to ascertain anything specific enough from merely talking with our suppliers. They are keeping their cards very close to their chests.

This post is thus to request any information at all from other forum members who may have some first hand knowledge of this topic. Perhaps you even have experience in or a knowledge of the CZ making process. And so I welcome all feedback. I’ve looked into the Skull Melting process which I understand to be the common production technique for CZ, but getting specific details has not so far been possible.

Specifically I’m trying to find out:

  1. what is the typical energy consumption (of electricity, gas, any other type or source) from the manufacture of a single large CZ crystal?

  2. what is the typical timeframe of the crystal-making process and what is the typical weight of the produced crystal?

  3. relevant to the cutting of that produced crystal, how much crystal can typically be cut into usable and saleable CZ V’s how much of that crystal goes to waste upon cutting?

  4. I personally dont know if the produced crystal is cut into CZ stones by hand or totally by an automated process (I would have thought that cutting say a large 1 or 2kg crystal output from the Skull Melting process would produce thousands of cut CZ stones and that therefore the whole process might be automated), but I’m also seeking a guide to the energy consumption of the cutting process?

Armed with this information (energy consumption of manufacture of the large crystal, and the cutting of that crystal) I could then calculate the average energy consumption (and cost) of producing say a 10-point CZ stone. This is overall what I’m trying to find out.

I apologise in advance if the question displays any ignorance of the topic, but that’s precisely why I have posted here - I dont now and I want and I need to learn about this from anyone with the time and energy and experience to explain or to share some of their knowledge (or suggestions).

Ask me anything relevant also.

Thanks in advance for all replies and feedback.

American Joe Wenkus invented CZ (the cubic zirconia diamond substitute). He was first to sell it in the synthetic gemstone market. He also invented the thermal conductivity tester used to differentiate CZ stones from diamonds.

He produced massive polycrystalline ingots by the skull melting method from which he harvested cuttable hunks. Joe was a well-known, well-liked member of the US crystal growth community (he was also the 1st President of the US Porsche Club). Joe is long gone, but I’m sure you can find folk still living who knew him through the AACG (American Association for Crystal Growth). I think he was also President of the AACG at one time.

The Russians have claimed inventing CZ and also the EFG crystal growth process. Both claims are at best dubious.

Robert, welcome to Orchid! Your question is very technical, but perhaps this reference may help:
Power Consumption of Skull Melting, Part I: Analytical Aspects and Experiments
C. Gross W. Assmus A. Muiznieks G. Raming A. Mühlbauer C. Stenzel
Pages: 319-328 First Published: 16 April 1999
They specifically discuss CZ creation energy use, but this article in Crystal is behind a paywall at Wiley:
An analytical model for a Skull melting set‐up is presented, which describes the power absorption in the melt and the losses in the inductor coil and the cold crucible. … Skull melting experiment. Analytical results are in good agreement with experimental (calorimetric) measurements of the power consumption in a typical Skull run (cubic stabilized zirconia), and with corresponding numerical simulations of the Skull process. The thermal conductivity of the Skull crust was estimated from experimental data.