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 Post subject: Re: ALERT: Testing platinum
PostPosted: Fri Oct 25, 2013 8:14 pm 
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I'm having the same problems testing an unmarked piece of silver colored jewelry. I appears very nice & well constructed & has a large high quality pearl mounted on the clasp. It also has a nice weight to it. I have tested it with all my gold acids---including my 22K acid too & it doesn't dissolve one tiny bit under any of them. It also doesn't dissolve whatsoever using my platinum acid tester...

It has failed every test for sterling silver---so it is definitely not that, nor is it rhodium plated over sterling, as I have rubbed a considerable corner of the metal on the stone for testing repeatedly with all these different acids, so the inner metal (if it were rhodium plated sterling) should have showed positive using the sterling acid test by then.

The only thing preventing me from deciding it MUST be platinum, is the possibility it could be stainless steel. It does have some magnetism, & I researched & stainless steel jewelry often has about 50% iron in it, which is magnetic. On the other hand, platinum jewelry often has 5% cobalt, which is also magnetic. (Pt950/Co = 950 parts platinum, 50 parts Cobalt)

From my research, I think BOTH platinum & stainless steel don't dissolve under any of the gold acid testers---so how do I tell if it is platinum or stainless steel ? One thing I haven't been able to determine in my research, is if stainless steel dissolves---or doesn't dissolve---using the platinum acid tester. Does anyone know if stainless steel dissolves using platinum acid tester ?

If stainless steel ALSO doesn't dissolve using platinum acid tester, does anyone have any other ideas on how I can tell if it is platinum or stainless steel ? I don't have any fancy testing equipment. I've definitely narrowed it down to just those 2 possibilities, but need help telling which one of those 2 it is for sure...


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 Post subject: Re: ALERT: Testing platinum
PostPosted: Sun Oct 27, 2013 7:50 am 
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Hi,
you can try with SG scale.........actually it's very easy to differentiate PT and SS by weight, their SG are really different......you should be able to evaluate it even by simply holding the piece in your hand...... :roll:

ciao
alberto

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 Post subject: Re: ALERT: Testing platinum
PostPosted: Sun Oct 27, 2013 10:10 am 
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Thank you Alberto. Although I don't regularly have need for an SG scale to justify buying one to test a single item.

As mentioned, it is quite hefty (and feels hefty in my hand). I is a 4-sturdy chain bracelet with a flower clasp & single fine (almost certainly Akoya) pearl. It weighs 31.5 grams.

I had someone reply on another forum regarding my question as to whether or not SS dissolved on the testing stone using the platinum acid tester. They said that whenever they tested SS, it dissolved with the platinum acid, when it didn't dissolve with the gold tester acids----even the 22K acid.

The marks on the testing stone don't dissolve at all---not one tiny bit, when I use the platinum testing acid.

I also tried the metal file on the edge of an inside edge, & it "grabbed" the metal with very little pressure at all, something I was also told indicated platinum, as you have to really apply pressure on the file to even get it to "bite" SS, which is much harder.

At this point, I'm 99+% sure it is platinum.

I'm including 3 pictures though, just to get your visual opinion as well (as to it's being heavy at 31.5 grams for its appearance). Thanks so much for your helpful response. :)


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DSC06326 (3) (500x498).jpg
DSC06326 (3) (500x498).jpg [ 155 KiB | Viewed 3278 times ]
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 Post subject: Re: ALERT: Testing platinum
PostPosted: Sun Oct 27, 2013 11:57 am 
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hmmmmm...............are you sure NO marks on that?? really??? please, search for them carefully, very often they're placed in hidden corners (although for that particular kinda bracelet they're almost always stamped on the clasp....) :roll: have a look in the red circle.....
that kinda piece reminds me very classic late 50's - 60's White gold stuffs.............. :roll:

ciao
alberto


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 Post subject: Re: ALERT: Testing platinum
PostPosted: Sun Oct 27, 2013 1:38 pm 
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Ah HAH !!! Wow Alberto, great catch ! --I looked there with a loupe & there are 2 stamps. The one you circled looks is a star in a circle. There is also a stamp on the left side of the clasp tongue that looks something like maybe a "B" or an "8" or something like that on the left side. It also looks very much like a single capital "P" in the right side of that stamp. There is a single flattened V shaped line below both of those, kind of like it's "underlining" both of the tiny B or 8, and P marks above it.

But I don't think it can possibly be white gold though, considering it passes every single gold acid test---including the 22K acid test. I believe only platinum, and 22K (& above) gold, and stainless steel can pass all the gold acid tests. Am I right ? And white gold never comes in 22K or higher karat purity, correct ?

But it also passes the platinum acid test, which I believe no gold of any karat would pass. I was told yesterday that even stainless steel (which passes all the gold acid tests) dissolves under platinum acid testing.

Do you know what the stamp of a star means ? I can't really say exactly what the other stamp is depicting for sure.

I really do appreciate your help Alberto. I'm learning a lot. :)


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