Emerald Grading

[raygem]

I am not a gemologist,so apologies for banging on about emeralds again.
I have heard that some Gem Labs. routinely grade emeralds as enhanced
or oiled because 95+% are.But I have also heard that unoiled,unenhanced
emeralds are also graded as enhanced because they could be unoiled or even
de-oiled and,after grading as unoiled,could then be oiled or re-oiled.
Does this make sense? I have also "heard" the reason the Labs. grade as such
is to avoid customer lawsuits if the emerald is subsequently oiled after grading.
Surely,if a photo is supplied and the stone is classified as "unoiled/unenhanced
at the time of testing",this covers the Lab. and the customer can compare the
photo against the stone being sold for a visual difference?Obviously,if it has been
oiled after certification,this is unethical,actually fraudulent, but is surely not the
prerogative of the Lab. to make such an assumption.I would appreciate comments
on whether what I have "heard" is actually the case and rely on you "wise ones"
for your guidance.I obviously have an agenda for this,but it is open and not hidden-
I have a large quantity of emerald that I believe is untreated and don't want it graded
as treated if it isn't.If a grading does come back as enhanced,is it reasonable to ask the
Lab. concerned[at extra cost,naturally] to identify the enhancing material?
In the same vein,if what I have "heard" is correct,then surely aqua,ruby,sapphire can
be heated after being graded as unheated.
Sorry folks,long-winded and hope I haven't bored you to tears.

[roshanravan]

actually i think you questioned and answered yourself, and some of what you heard is true but not all
Oiled Treatment or Enhancement in Emerald is a very common practice, high quality, untreated emeralds are rare. and oil in fractures can dry in time and re-oiling can be done. also reputable labs can identify dried oil or untreated ones. they don't just assume all emerald enhanced, what you saying to avoiding customer lawsuits is not ture, this concept is nonsense, they already avoid any kind of lawsuits with their disclaimer, even if they make a mistake in identifying. picture in lab report does not prove anything because it does not include stones microscopic observations and one can not tell from a picture if the stone has been altered or not.

[Barbra Voltaire, FGG]

An emerald can only be enhanced with oils, resins or polymers if it contains surface reaching fractures.
That is what most labs look for: fractures which break the surface.

One can often detect remnants of fillers within the surface reaching fractures.

If an emerald has no surface reaching fractures, there is nowhere for fillers to enter the emerald.

A personally trust AGL with all my treatment determinations.

[raygem]

Thanks Rosh and Barbra for the info.It makes good sense.
I do have a lot of material with no fractures,so I will send
that to my customer first.
I did see certificates from AGL confirming no treatment,so
thank you for confirming the credibility of AGL.

[roshanravan]

Thanks Rosh and Barbra for the info.It makes good sense.
I do have a lot of material with no fractures,so I will send
that to my customer first.
I did see certificates from AGL confirming no treatment,so
thank you for confirming the credibility of AGL.

Today most traders are concern about resin filled emeralds, as i said oiling is a very common practice. if quality of emerald worth getting lab report most important value factors other than indicating resin/oil is that knowing how insignificant/Moderate/Significant filler is in fissures or fractures. some traders refer to Emeralds with no surface reaching fracture as Crystal Quality, good green color in this quality is indeed rare.

[raygem]

Thanks again Farshid-seems like I do have a lot of "crystal",so
it looks like it will be worth certificating.

[raygem]

Hi Farshid/Barbra
I have been asking around and doing some googling.I am not trying to
teach my grandmother[or you wise ones] to suck eggs,but some
ignoramuses[ignorami?] like me,reading this post may find the following
useful.
It seems that a couple of simple ways to detect oiling[specifically,
not Opticon etc] is to:
1.Leave the emerald/s in warm water for a few hours-an oily surface film
will appear.
or
2.[Thanks Duncan]Heat the emerald slowly on some paper.Simplest way is
to expose it to bright sunlight for a few hours and the paper will become
oil-stained.NB-Do not try this in England!! I am a Pom and know that you
may have to wait months for a sunny day!

With a parcel,especially if cedarwood oil or Canada balsam has been used,
the smell could be noticeable.
But,please note,if it is an emerald you plan on wearing,tests 1 or 2 may result
in you having to have your emerald re-oiled.
The particular reason for my interest is that I am 99% sure my emeralds have not
been oiled and 99.99% sure they have not been treated with polymers.
However,it is possible that oil could have been used in the cutting process,so it
looks like I need to soak in acetone before sending to a GemLab.The cutter has
sadly passed away,so I cannot check with him.

As well as AGL[USA], for those in Europe,GGTL Lab in Liechtenstein have been
highly recommended to me.

[Barbra Voltaire, FGG]

Uhmmm, couldn't you also just check for surface reaching fractures with the microscope?
An emerald's value is not only a function of level of treatment, but also it's aesthetic appeal.
If an emerald is untreated and ugly, it is not going to be valuable

[Duncan Miller]

Last week Ray showed me some of his emeralds. They are far from ugly, so it is important for him to get accurate lab reports as that will affect the value considerably. I suggested he might experiment with the heating test, but really a reliable lab's report identifying the actual nature of any oiling or fracture filling is the only way to go. A vague statement like 'clarity enhanced' is not sufficient for the goods he has.

I don't think anyone has answered his question as to whether a formerly oiled emerald that has been 'de-oiled' with solvents can be described as 'unoiled'. My presumption is that if oil (or any other fracture filling) is no longer present then it would be fair to describe the goods as 'unoiled'. What is the consensus opinion?

[raygem]

Thanks Barbra and Duncan
I have a good gem microscope and will do what you suggested..

[Barbra Voltaire, FGG]

Duncan, that would be a great question for Christopher Smith. He (in my opinion) has the most sophisticated "nose" in the biz to sniff out treatments.

[raygem]

Barbra,just double-checking.Are you referring to cracks on the top
surface or on any surface? I assume it is anywhere.

[roshanravan]

Hi Farshid/Barbra
I have been asking around and doing some googling.I am not trying to
teach my grandmother[or you wise ones] to suck eggs,but some
ignoramuses[ignorami?] like me,reading this post may find the following
useful.
It seems that a couple of simple ways to detect oiling[specifically,
not Opticon etc] is to:
1.Leave the emerald/s in warm water for a few hours-an oily surface film
will appear.
or
2.[Thanks Duncan]Heat the emerald slowly on some paper.Simplest way is
to expose it to bright sunlight for a few hours and the paper will become
oil-stained.NB-Do not try this in England!! I am a Pom and know that you
may have to wait months for a sunny day!

With a parcel,especially if cedarwood oil or Canada balsam has been used,
the smell could be noticeable.
But,please note,if it is an emerald you plan on wearing,tests 1 or 2 may result
in you having to have your emerald re-oiled.
The particular reason for my interest is that I am 99% sure my emeralds have not
been oiled and 99.99% sure they have not been treated with polymers.
However,it is possible that oil could have been used in the cutting process,so it
looks like I need to soak in acetone before sending to a GemLab.The cutter has
sadly passed away,so I cannot check with him.

these procedures you mentioned are not practical ways to identify oiling in labs,

i think this article will give you a pretty good idea how it gets done:
[pdfview]http://www.ssef.ch/uploads/media/1999_Filler_Identification_Emerald__J_Gemmo_ruduce_file.pdf[/pdfview]

As well as AGL[USA], for those in Europe,GGTL Lab in Liechtenstein have been
highly recommended to me.

do not forget SSEF and Gubelin also GemResearch Swisslab (GRS)

....I don't think anyone has answered his question as to whether a formerly oiled emerald that has been 'de-oiled' with solvents can be described as 'unoiled'. My presumption is that if oil (or any other fracture filling) is no longer present then it would be fair to describe the goods as 'unoiled'. What is the consensus opinion?

you are making things so complicated, oil filling treatment is not permanent so it can leaves traces of dried oil in some fissures and fractures. de-oiling process can be done, even few labs like GGTL Lab in Liechtenstein offer such a service (procedure is very like oiling, it consist heat & pressure but with some acid and solvent), anyways if in specimen there are no traces of dried oil then no one can tell if it was de-oiled or not! and there is no such unoiled term in trade using to describe the emeralds.

[raygem]

Thanks Roshanravan
I don't have this equipment so I guess I will treat all my stones with hydrochloric or
oxalic acid[should remove "rust" stains anyway] and then soak in methylated spirits
or acetone so that I then know there is no oil present.

[roshanravan]

Thanks Roshanravan
I don't have this equipment so I guess I will treat all my stones with hydrochloric or
oxalic acid[should remove "rust" stains anyway] and then soak in methylated spirits
or acetone so that I then know there is no oil present.

Ray if you want to do some tests for yourself and your knowlage its alright and usefull but as Barbra said Oil Treatment has no great effect on value, as i said before these days every one care about resins and there is no way to de-resin them so they ask for Lab Report.

As for the customers i am pretty sure they would not take anyone word or get satisfed just by tests like soaking in solvent except a Lab Report, for very high value product they even ask for re-submission stone to another lab to make sure no treatment has been done after issuing the previous report.

i myself have seen a high value Emerald with 3 different lab reports which has been sold two times and every time the buyer requested a new lab report with origin before finalizing the transaction.

All i am saying is if you have good product and as you said you have Crystal type quality then dont worry about oiling, experts care more for quality than oiling (except resin). unless its AAA+ color and clarity quality then no oil matters.

for your information, since sixteenth century when Spanish conquistadors brought emeralds from the Chivor and Muzo mines in Colombia, after mining and polishing they would have kept emeralds in oil for transportation to prevent abrasion & scratching themselves. traders still use this method for transportation as it is the safest way for emerald for transportation. but still there are some goods that has not been oiled after polishing which traders mostly do that for very high quality products and in that case soon after polishing they get lab report to prove that, this is not common for poor to good quality ones.