# making gold testing solution



## PRECIOUS METALS

hi does any one know how to make the gold testing solution for 10kt, 14kt, 18kt, 24KT TESTING SOLUTION .SAY YOU GOT A 14KT GOLD CHAIN SCRACTH IT ON THE GOLD TESTING ROCK, THEN ADD THE SOLUTION .


how would you make that solution and whats in it


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## goldsilverpro

Here are the formulas that came with a test kit I once bought. It came with empty glass bottles and gave the formulas to make up the solutions.

10K - 3/4 ounce, by volume, nitric acid - 1/4 ounce distilled water 

14K - 4/5 ounce nitric acid - 1/5 ounce dist. water - 10 drops of hydrochloric acid 

18K - 1/5 ounce nitric acid - 1/5 ounce dist. water - 3/5 ounce hydrochloric acid 

Silver test soln. - Dissolve 20 grams of potassium dichromate in 3/4 ounce of nitric acid mixed with 1/4 ounce of distilled water. A drop of this on a silver alloy will turn red, the higher the silver, the redder the drop. You have to see it

I have seen other different formulas.


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## Noxx

This was my question on this post:
http://goldrefiningforum.com/phpBB3/viewtopic.php?t=307
Take a look and you should find infos.


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## Noxx

Well, we don't know Nitric Acid concentration with this receipe...


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## PRECIOUS METALS

WOULD YOU HAVE THAT MIX BREAKDOWN IN GRAMS


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## goldsilverpro

I had problems figuring out what you guys meant. The formulas are in fluid ounces, not weight ounces. There are 29.6 mL in a fluid ounce. I just copied it off the instructions. Please not that I have never mixed these up. I always used the various pre-mixed solutions that I bought from companies that sell jeweler's supplies. I also see them on eBay. They also have 22KT. They're cheap.

If you can measure mL, milliliters, that would be the easiest. Here are the exact numbers. You can probably round them off. Just measure them as accurately as you can. Fluid ozs. don't convert to mL that evenly.

10KT - 22.2 mL nitric - 7.4 mL distilled water
14KT - 23.7 mL nitric - 5.9 mL distilled water - 10 drops hydrochloric
18KT - 5.9 mL nitric - 5.9mL distilled water - 17.8 mL hydrochloric
Silver - 20 grams potassium dichromate - 22.2 mL nitric - 7.4 ml distilled water


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## PRECIOUS METALS

you the best thanks


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## PRECIOUS METALS

thanks for the info 

just one question on the 14k is it 10 drops hcl or 10 ml


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## goldsilverpro

Drops. 10 drops is about .5 mL or, a little less. Depends on the eyedropper.


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## Noxx

I was wondering, do the Nitric Acid concentration affects anything at all ?
Or maybe I'm a little bit mixed up ??


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## goldsilverpro

Noxx,

If I understand your question right, the answer is yes.

When you apply the acid to the streaks on the touchstone, you are looking for the amount of attack, the rate of attack, and the color produced. Stronger or weaker nitric will effect these. It's a visual thing. You compare these unknown streaks, side by side, at the same time, with streaks made with gold of known karats, usually from gold testing needles or from gold objects that you know the karat of. It's really pretty simple, once you get the hang of it. Play with it. Make streaks with different things and try all the acids on them. Be very careful not to cross contaminate the acids.

Where are you in Quebec? I was stationed in the Air Force, for 3 years, near Caribou, Maine, about 40 miles from Quebec. Spent most of my time off in Quebec. Beautiful but cold. Went to the winter carnival in Quebec City one year. Great fun. Beautiful women.


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## jimdoc

Noxx,
Do you mean the concentration of the nitric that you buy, or start out with
like 70%? Or if a lower concentration will work or be better?


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## goldsilverpro

The formulas I gave are based on reagent grade or technical grade nitric acid, although, the technical grade is a little weaker. Since this is a comparison thing - known karat vs unknown - slight variations in nitric strength shouldn't make that much difference. When I use the commercial test acids, there are slight differences in strength. When I buy a fresh one, I have to get used to it's differences. Also, the acids containing hydrochloric will get weaker over time.

The main things are that your 10KT acid doesn't dissolve a 14KT streak or the 14KT acid doesn't dissolve an 18KT streak. I should say dissolve quickly. If you let them sit long enough, there could be some attack. For this reason, I usually cut my observation off at, say, 10 seconds.


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## Noxx

Ok now I understand ! Like you say it's a comparison thing. So I absolutly need needles wich are «certified» 10k gold.

I'm about 10 mins from Quebec city. Yes it's cold. But it's beautiful. Did you ever eat freshly made Maple tofty ? Soooo good !


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## Noxx

I would like to know if test stones are special stones. Is it possible to use a fine grit sand paper ? ( The one used for metals )
Thanks


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## PRECIOUS METALS

tester


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## Noxx

What do you mean ? I don't understand...


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## PRECIOUS METALS

you were asking about the gold testing rock,if im not mistaken,you scrape the gold on the rock,its not exactly a rock they just call it that,then add the acid


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## Noxx

OK then if it not a rock, can I use something else ? Or this rock has something special in it ?
Thanks


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## PRECIOUS METALS

it looks like this you can buy it in any jewlery supply


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## toadiesop

Hey Holywood,

I love your posts, but I do have to say this..... please take notice.







It's just hard to read. Thanks and keep up the good work. 

IT REALLY HURTS THE EYES WHEN YOU HAVE TO READ SOMETHING ALL IN CAPS!! :shock:


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## Noxx

Lol !
Well I already asked him twice...


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## PRECIOUS METALS

sorry guys bad habet didnt notice .


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## MacDaddy

Noxx said:


> I would like to know if test stones are special stones. Is it possible to use a fine grit sand paper ? ( The one used for metals )
> Thanks



Yes, the testing stone is a special type, but I can't remember the name. It is chosen for it's color consistency and lack of absorbtion.
The stone is inexpensive and will last a lifetime. Why bother with sandpaper?


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## MacDaddy

Noxx said:


> I would like to know if test stones are special stones. Is it possible to use a fine grit sand paper ? ( The one used for metals )
> Thanks



Black Lydian slate is the touchstone. It is harder than the metals being tested as well as consistency and lack of absorbtion.


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## PRECIOUS METALS

yes special stone you cant use sandpaper ,it will be a mess

the solution your adding that are in the test bottle is nitric /hcl


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## Anonymous

Does anyone know how to make 9k gold solution? as this is the most commonly used here in New Zealand. cheers


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## goldsilverpro

GoldXchangeNZ,

Actually, the 10, 14, 18, and 22k acids aren't specific to those karats. The important thing is how the acids react to those specific karats. I would think that 10K acid could easily be used to test 9K gold. You should use something that you know to be 9K and then compare the reaction, side-by-side, using the 10K acid, with the unknown. If this isn't sensitive enough for you, dilute some of the 10K acid, just a tiny bit, with distilled water. The 10K acid is usually just nitric and water anyway. The touchstone is a comparison method and not an absolute, "this will happen", method.


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## Anonymous

thanks for that. I thought that 10k would work but just making sure. cheers


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## uranian

hi gold refiners, first post so greets to all  

useful thread here, as i'm about to make my first few ml of aqua regia, and have been reading this with interest. one question i have is in regard to water; reading around other info on aqua regia, it's just 3:1 with the acids, no mention of water. yet here i read about adding water. wondering if anyone knows if there's any useful function to adding water, or if it's good to go with just 3:1 acids.


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## Harold_V

uranian said:
 

> hi gold refiners, first post so greets to all
> 
> useful thread here, as i'm about to make my first few ml of aqua regia, and have been reading this with interest. one question i have is in regard to water; reading around other info on aqua regia, it's just 3:1 with the acids, no mention of water. yet here i read about adding water. wondering if anyone knows if there's any useful function to adding water, or if it's good to go with just 3:1 acids.


I suggest you not consider 3:1 for aqua regia. Two reasons. Depending on the level of concentration of either of the two acids, you may be lacking in HCl in order to fully consume the volume of nitric. Secondly, unlike excess nitric, excess HCl does no harm--------so start with a mix of 1 nitric to 4 HCl, which will insure that you consume all of the nitric (assuming you have not added excessive nitric).

The addition of water results in the hydronium ion---supposedly with the effect of extending the amount of work a given amount of acid can perform. Not being a chemist, I am not able to confirm or deny. However, my repeated experience in making electrolyte for the silver cell indicates to me that it is true. Nitric in concentrated form is slow to dissolve silver, yet is exceedingly fast when diluted by an equal amount of (distilled) water, which was my routine. 

Harold


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## uranian

i've got more of each acid than i'll ever use, so i'm not really concerned about volumes used, but thanks for the thought. your experience that nitric acid mixed with water dissolves silver faster is useful stuff too. i'll try both and update as i go.


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## qst42know

Can we have a Dunce smiley on the forum?

You just received advice from one of the key members of this forum. Advice given to help you achieve success and it passed right through your head. :roll:


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## Harold_V

uranian said:


> i've got more of each acid than i'll ever use, so i'm not really concerned about volumes used, but thanks for the thought


You're very adept at missing the point, my friend. 

Harold


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## nickvc

qst42know said:


> Can we have a Dunce smiley on the forum?
> 
> You just received advice from one of the key members of this forum. Advice given to help you achieve success and it passed right through your head. :roll:


And a like button? :roll:


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## Oz

I am going to cry foul here on all of you except uranian. It was his first post, of course he does not understand the value of what Harold wrote and why it is important. 

But lickidy split he was labeled a dunce (stupid) but no advice was offered to explain why he misunderstood the value of what was presented. It is fine to tell someone they are wrong or do not understand. But it is also wrong to say that, and not offer an explanation as to why they are wrong.

I am tired and must go to bed but to put it simply uranian, Harold was trying to prevent you from having excess nitric in your final solution which is a chore to remove before precipitating your gold and can often be avoided.

I do not mean to seem harsh but maybe due to lack of sleep I only saw the criticism of someones lack of knowledge, and no signs of helping him/her to grasp what was being offered or giving clarification as to what they missed.


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## uranian

friendly place, i'll not bother then. what's hard to understand that i've got more acid than i'll ever use, so i'm not concerned about saving acids? i have 2.5 liters of each acid, and i'll never need more than 100ml of aqua regia in my entire life i imagine. 

we need a goodbye smiley, too :|


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## Oz

Now I regret what I wrote. My apologies to Harold, Nick, and qst42know. I must have missed something that you all saw. 

Uranian, on the slim chance that you may actually become a contributor here in the future I will say it more clearly. It is not about the acids you have available to you (hell you could have free acids into perpetuity), having the wrong balance means you have problems precipitating your gold. That is what you want right?

I must say that after I stood up for you as a new member that may not understand the value of what was presented, then seeing your reply, I have lost all interest in helping you if you care to take that kind of attitude. You are a fish out of water, and I tried to give you a drink.


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## qst42know

The dunce smiley comment was sarcastic, harsh and served no purpose. It did nothing to convince you to pay attention to the help that was offered. For that I apologize.

What I saw was an flippant attitude towards sage advice.


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## goldenchild

goldsilverpro said:


> The formulas I gave are based on reagent grade or technical grade nitric acid, although, the technical grade is a little weaker. Since this is a comparison thing - known karat vs unknown - slight variations in nitric strength shouldn't make that much difference.



I think GSP brings up a very good point here. In my opinion its not worth making your own solutions. There are too many variables in making your own testing solutions that could be very costly(as in you lose money :!: ). Also mentioned in this thread is how many drops of HCL and distilled water are needed and that it can vary by eyedroppers. These should be very precise no? This is even before we start talking about the HCL. Is it lab grade HCL or the kind that you get at the hardware store that may contain contaminants(like metals) :?: I think you're better off just buying the little bottles. But again this is just my opinion.


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## goldsilverpro

The ready-made test solutions are very inexpensive and easy to find. However, since the 14K and 18K both contain HCl and HNO3, chemical reactions occur between the two and their strength will tend to change over time. In my experience, every ready-made solution I've bought reacted a bit differently, as far as speed is concerned. This is probably due to age or the difference in the formulas used by the different manufacturers. But, since this is a COMPARISON method (not an absolute method) between a standard and an unknown, all of that doesn't make much difference unless the solution are quite old and are too slow. For this reason, the make up of the homemade solutions don't have to be terribly precise.


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## kmggold

Interesting post. For determining purity of mixed karat scrap gold jewellery items using acid testing, I find the following to be essential.
Low karat gold I use nitric acid only, technical grade, assay 65-75%. The rate of dissolution and colour change is typically enough to determine 8-14 karat. Nitric alone will differentiate between pre-1982 14k stamped items that are 13.5k and 14k plumb. Nitric alone will immediately determine fake Hong Kong plated junk stamped 10k and 14k.
Then for the mid karat items I use a mixture of water, nitric and hydrochloric - one part hydrochloric, fifty parts nitric, and 12 parts water. This will immediately dissolve the lower karat stuff and slowly dissolve the 14-18k range. You have to be quick, but there is enough time to differentiate between 14k jewelry, dental, 17.5k (pre-1982), 18k, and some placer gold (nuggets). Once again the rate of dissolution and color change is significant enough to determine purity with good confidence.
Some literature suggests that testing higher karat material with acids loses accuracy. I have found this to be true, but only with bought, pre-mixed bottles of acid. Home made agua regia and quasi-aqua regia produces excellent results when prepared and used fresh. It is far to strong for purities less than 18k and will dissolve immediately on contact.
I use three different recipes for the high karats and platinum. Two "high test" recipes, and one of true aqua regia. 
These are very very dangerous - handle with care! They will burn everything including you!
ALWAYS ADD ACID TO WATER - NEVER ADD WATER TO ACID!
one part nitric, 3 parts hydrochloric
one part nitric, 4 parts hydrochloric
and true agua regia, 9 parts nitric and 41 parts hydrochloric.
These will test, very accurately, all karat gold between 18k and 24k. Once again, by comparing dissolution rates and color changes. Although color change at high karat can be minimal. I also look at the scratch with a loupe to look for bubbling of alloyed copper and zinc, and white residue from alloyed silver.
For testing high karats I will use one line of each acid on all samples to quickly (very quickly if the karat is 22k or less) determine relative purity.
Using fresh homemade batches of acid can accurately differentiate between the sub-standard undercarated material from India, stamped 22k, but in reality is somewhere between 18k and 19k. There has been pounds and pounds of this stuff surface in Vancouver, Edmonton and Toronto. A lot of gold buyers took a hit on these items because they did not know how to accurately test the high karats.
When testing pure gold, if you have enough experience, you don't even need acid. Simply making the scratch with pure gold on a touchstone will tell you its pure. Alloyed gold "draws" on the stone like a pencil on paper. Pure gold will not "draw", it merely leaves very small flakes of gold on the stone.
If all you test is 10k, 14k, and 18k, then the bought, pre-mixed bottles may work for you. But don't use them on high karat or you might get burned! 
All acid testing is relative to your known samples - so keep good reference samples!
I hope this helps. Please visit our web page http://www.kmggold.com for more information in our FAQ pages.
Mike


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## slouma37

Hi all,
as histonishing as it appears, i sometimes simply use a ceramic stripped CPU as a touch stone. It works just great ! Another way of recycling ceramic cpu's ? LMAO as a little touch stone cost's like 13€ like 18 US$ in Belgium.

Salim


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## kmggold

A very inexpensive alternative to a "touchstone" is a piece of frosted (sandblasted) glass. Available at most recycled building supply shops and occasionally at the Goodwill, Salvation Army thrift stores etc. 
You can also buy this type of glass at building hardware stores. 
Dark coloured glass is best for ease of anaysis...
You only need a small square of it. 
Mike
http://www.kmggold.com


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## newb

Are there more solution formulas? 
I found the answer of formulas to 18K but I'd like more, ie 20, 22, 24k

10K - 3/4 ounce, by volume, nitric acid - 1/4 ounce distilled water 
14K - 4/5 ounce nitric acid - 1/5 ounce dist. water - 10 drops of hydrochloric acid 
18K - 1/5 ounce nitric acid - 1/5 ounce dist. water - 3/5 ounce hydrochloric acid

Does anyone know the formulas for 20,22,and 24???????? either in oz, ml or drops will do.


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## newb

One says 
18KT - 5.9 mL nitric - 5.9mL distilled water - *17.8 mL hydrochloric*

The another says 
18K - 5.9ml nitric to 5.9ml distilled water to *22.2ml HCL*
for 22K i just used 1 part nitric to 4 parts HCL

Surely there's a standard somewhere right??
Where & what is it??


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## samuel-a

newb said:


> One says
> 18KT - 5.9 mL nitric - 5.9mL distilled water - *17.8 mL hydrochloric*
> 
> The another says
> 18K - 5.9ml nitric to 5.9ml distilled water to *22.2ml HCL*
> for 22K i just used 1 part nitric to 4 parts HCL
> 
> Surely there's a standard somewhere right??
> Where & what is it??



newb

Layoff the idea of having a "standart" testing solution for a specific karatage... It's all about comparison with your standart 18K 21K 22K needles (or other gold standart you have).
It' doesn't really matter what's the ratio of the AR you make, the reaction time is the point here. :idea:


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## newb

Reaction time??
I picked the name newb because I am just that. A newb to gold testing and solutions.
I'm trying to learn how to test the K of gold and make my own solutions to do so. There's not a book on it or a class to attend here so I'm looking online.
Any and all advise on learning this will be appreciated.


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## samuel-a

newb said:


> Reaction time??
> I picked the name newb because I am just that. A newb to gold testing and solutions.
> I'm trying to learn how to test the K of gold and make my own solutions to do so. There's not a book on it or a class to attend here so I'm looking online.
> Any and all advise on learning this will be appreciated.




The point of which the test strike dissipate, in comparison to that of your standart karat piece.


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## qst42know

newb said:


> Reaction time??
> I picked the name newb because I am just that. A newb to gold testing and solutions.
> I'm trying to learn how to test the K of gold and make my own solutions to do so. There's not a book on it or a class to attend here so I'm looking online.
> Any and all advise on learning this will be appreciated.



Here is a good explaination.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=3624#p30753


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## bogarasjoe

Hello guys!

Have you some information about 8 karat test solution? What concentration of nitric is applied? 
I've read the 10 karat solution recipe, maybe it would work on 8k. But what about the 8 k test solution?


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## butcher

If you used an 8 karat gold needle to make a scratch on your stone, and a scratch from the suspected jewelry next to it, (a 10K needle could also be used to see if it was below 10K), and then used the 10k testing solution on both marks to see if one dissolved before the other or both stay the same, you could determine if the jewelry was 8K or not, then you could retest with other karat gold needles to see if it may be higher percentage of gold or not.

Search for a post by Pawnbroker Bob (Pawnbrokers guide to testing jewelry is a very handy few pages to learn testing jewelry) he goes into great detail with what you are looking for, Hoke's also has a book on testing.

I know a gold buyer who is very good at testing for gold and he is also good at telling the karat, and all he uses is nitric acid and a scratch of the jewelry on a black volcanic glass stone (no test needle scratch used), he can recognize the karat by how the nitric acid reacts to the gold scratch, by how much copper and silver and base metals the nitric dissolves and how much gold is left, he has been testing this way for many years, and is very good at it.


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## bogarasjoe

Thanks butcher for useful infos!
Unfortunately, i don't have test stone and needles.
I have just nitric acid, and a mini Maria Theresia coin. I dropped a very little nitric on it. The coin has gone brownish, not green. So i think it is gold, not just a gilded copper one. I found on the internet a same coin, and they are saying it is 8 karats. 
A jeweler tested it with 14 karats test probe, but it was negative. So it is maybe less karat (or gilded copper? dont think).


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## butcher

If you have a ceramic CPU you could use it for a stone, a rough part of an old ceramic plate, or the rough area of the bottom of your black ceramic coffee cup would work also, the test scratch could be from another piece of jewelry of known karat, this would give you something to compare it to, or you could just try to decipher the scratch for your coin alone, you would see the scratch fade as the base metals dissolved in the nitric, he drop of acid turning blue to green in the acid, a little over half of the scratch would dissolve if the coin was around 8k, but should not fade completely away if gold is left from the coin, also you would not want any chlorides in the nitric acid you were using for testing with, I would not use homemade nitric acid, (unless it was distilled and silver nitrate was used to remove any chlorides).

I am not the best source for answering questions on testing jewelry.

Pawn Broker Bobs little book on testing metals is what you need.


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## bogarasjoe

LoL butcher!!! Ceramic CPU for test stone..... Excellent idea!!!!! Of course i have .
Test is comming soon. I'll try it with the 10 K test solution on a ceramic piece. 
Thanks a lot! 
Regards, Dave


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