Fake ametrine from china on eBay
6th Jul 2014 17:52 UTCAlex Hahnenberg
I deal specially in ametrine, especially the Bolivian material from the Anahi. So when I bought some fake material recently I was very chagrined. I have recently come across fake ametrine clusters from china on eBay. There are 3 sellers with this material that I've seen so far. I had several experts examine the one I bought and the eBay seller agreed to let me return it. However I've contacted Ebay informed them of the fraud and nothing has been done. The sellers continue to sell this lab grown material. So if you see ametrine clusters from china or brazil be very wary. There is very little natural ametrine from brazil. However there is some real ametrine on eBay from Brazil from San Jose de safira. Anyway keep your eyes open! Alex
Rock et al,
I'm quite sure that y'all have seem more quartz than I have had hot breakfasts :-) But the more I look at Alex's pics, the more sure I am that this piece is not lab synthesised. The business of growing quartz crystals by hydrothermal process has been well understood for over 50 years. Crystals of high purity and good size are grown on an industrial scale. I can see that there is a little similarity between Alex's material and the 'waste' crystalisation that occurs in a flux melt crystal manufacture - but that is not the method by which quartz is synthesised.
Having taken a closer look at Alex's pics and scratched my head, there is some similarity with a thumbnail of of amethyst on agate in my own little collection. The history of my piece (which I am satisfied could not be lab grown nor a composite) gives another link too; I bought it from an eminent gemmologist who bought it in China during a trip there in the 1980's.
I'd place a small bet that this is basically the same as Alex's stuff but that the agatised base is more pronounced with my specimen because the its base and sides have been cut and polished to show off to advantage the agate structure.
Both specimens show some golden brown colour in the microcrystalisation. Citrine? That thought had not occurred to me until today. Whatever, there is no way that my piece should be called ametrine and, from what one can see, it's stretching a point to so label Alex's piece too.
Not all ametrine is of the high quality and definite characteristics that the Anahi crystals and (subtly different) synthesised ametrine show. Where one should draw the border between what is ametrine and what is not to be so-called seems a little unclear. For me, to be called ametrine requires purple and yellow/gold colouration to be present in the same quartz crystal and not with a colour difference showing between different different crystals in the same cluster.
A key difference between the natural form of ametrine and high quality synthetic manufacture is the difference in the crystal habit. .
Stephanie raises the question as to whether an 'ametrine' quartz could be produced artificially in another way. Yes and such work was being done experimentally in the early 80's by Kurt Nassau and others. It requires quartz which had a specific Fe+++ impurity before being turned to amethyst by irradiation (natural or otherwise). Localised heating of such material to 400-450 deg C will then turn the heated part to citrine - a change that can be reversed by irradiation. In this processing, because of the thermal gradient within the quartz, the yellow/purple boundary cannot be sharp. In the Russian-invented method of synthesising ametrine, used on a commecial scale, firstly a citrine crystal is grown, then turning its outer layer first colourless and then purple by gamma irradiation (Cobalt-60 source). This is the only way I have seen reported to produce ametrine of the quality of the Anahi natural ametrine.
Bottom line..... I think Alex's specimen is likely to be of natural origin. Whether or not it has been treated (selective use of heat?) can't be ascertained from the pics but IMHO I'll guess that it has not. .
I'm quite sure that y'all have seem more quartz than I have had hot breakfasts :-) But the more I look at Alex's pics, the more sure I am that this piece is not lab synthesised. The business of growing quartz crystals by hydrothermal process has been well understood for over 50 years. Crystals of high purity and good size are grown on an industrial scale. I can see that there is a little similarity between Alex's material and the 'waste' crystalisation that occurs in a flux melt crystal manufacture - but that is not the method by which quartz is synthesised.
Having taken a closer look at Alex's pics and scratched my head, there is some similarity with a thumbnail of of amethyst on agate in my own little collection. The history of my piece (which I am satisfied could not be lab grown nor a composite) gives another link too; I bought it from an eminent gemmologist who bought it in China during a trip there in the 1980's.
I'd place a small bet that this is basically the same as Alex's stuff but that the agatised base is more pronounced with my specimen because the its base and sides have been cut and polished to show off to advantage the agate structure.
Both specimens show some golden brown colour in the microcrystalisation. Citrine? That thought had not occurred to me until today. Whatever, there is no way that my piece should be called ametrine and, from what one can see, it's stretching a point to so label Alex's piece too.
Not all ametrine is of the high quality and definite characteristics that the Anahi crystals and (subtly different) synthesised ametrine show. Where one should draw the border between what is ametrine and what is not to be so-called seems a little unclear. For me, to be called ametrine requires purple and yellow/gold colouration to be present in the same quartz crystal and not with a colour difference showing between different different crystals in the same cluster.
A key difference between the natural form of ametrine and high quality synthetic manufacture is the difference in the crystal habit. .
Stephanie raises the question as to whether an 'ametrine' quartz could be produced artificially in another way. Yes and such work was being done experimentally in the early 80's by Kurt Nassau and others. It requires quartz which had a specific Fe+++ impurity before being turned to amethyst by irradiation (natural or otherwise). Localised heating of such material to 400-450 deg C will then turn the heated part to citrine - a change that can be reversed by irradiation. In this processing, because of the thermal gradient within the quartz, the yellow/purple boundary cannot be sharp. In the Russian-invented method of synthesising ametrine, used on a commecial scale, firstly a citrine crystal is grown, then turning its outer layer first colourless and then purple by gamma irradiation (Cobalt-60 source). This is the only way I have seen reported to produce ametrine of the quality of the Anahi natural ametrine.
Bottom line..... I think Alex's specimen is likely to be of natural origin. Whether or not it has been treated (selective use of heat?) can't be ascertained from the pics but IMHO I'll guess that it has not. .
