Unknown Platinum Hallmark

[ipsilateral]

Anyone know what country this platinum hallmark comes from? The mark is P.m on left and 900 on right.

 

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[Mackaydon]

It is my understanding that when identifying an item as being platinum, it’s important to check the shape and contents of the fineness mark. If the shape is anything other than what is shown below, it isn’t platinum. As you can see, your '900' does not comply with the mark below; Hopefully, for you, I may be wrong.

Platinum fineness
​

Don........
PS: Admittedly, my comment refers to UK marks, specifically.

 

[ipsilateral]

I conducted two tests on the metal to determine it was platinum. Heat test. Heated ring to red hot repeatedly with torch and no oxidation of the metal occurred. Acid test. Tested ring with acid of varying concentrations-- up to one used to test 22K gold. Metal was non-reactive. I'm not an expert, but I believe it is platinum. My experience with precious metal hallmarks is that there is quite a bit of variability in hallmarks. English marks are some of the most rigid in the world. If only they were all that straightforward.. If there are other tests I should do, someone let me know.

 

[Mackaydon]

High-end and specialist precious metal dealers use XRF (X-ray fluorescence) testing to accurately identify the platinum content of jewellery. Inductively coupled plasma, optical emission spectrometry is used by assay offices during the hallmarking process.
Don........

 

[ipsilateral]

Well yeah, I'm well aware of that, but I don't happen to have $20,000 sitting around my workshop. Mostly I'm just interested in the hallmark if anyone has run into it before, not fine points of metal testing in which I'm fairly well read.

 

[Mackaydon]

You asked.
I let you know.
You're welcome.
Don.

 

[ipsilateral]

Looks like it was possibly a Japanese platinum hallmark. Gold fever - Friendly Metal Detecting Forums