Platinum, the metal. A "hard" question.
November 11, 2010 2:01 PM   Subscribe

Where can I go to learn how to verify the authenticity of platinum?

I need to learn how to verify the authenticity of platinum bullion (coins, bars, etc.). Where would I go to obtain expert-level training?

Secondly, is there a professional designation for someone who has this level of expertise and or documented training?

Also, is there some service that can extract and/or verify the content of platinum contained in scrap?
posted by Rafaelloello to Work & Money (10 answers total) 1 user marked this as a favorite
A materials lab can take a shot with an XRF to determine platinum content. Our lab charges $25 a shot.
posted by sanka at 2:08 PM on November 11, 2010

If it's pure platinum, you can always do it the old fashioned way. Just weigh it, then drop it in a graduated cylinder and see how much water it displaces. Divide the mass by the volume and you have the density. It should be 21.45 g/cm^3

There's not much that's more dense than platinum is.
posted by empath at 2:10 PM on November 11, 2010

Response by poster: Archimedes principle. I almost forgot simple. Is platinum denser than lead?
posted by Rafaelloello at 2:20 PM on November 11, 2010

Response by poster: I meant tungsten, not lead. Still a great and simple idea. Tungsten is very close to gold, but slightly less dense than platinum.
posted by Rafaelloello at 2:26 PM on November 11, 2010

Density will not rule out the possibility of a platinum group alloy (iridium and osmium are denser and cheaper than platinum).
posted by ssg at 2:37 PM on November 11, 2010

Do you want to check out jewelry, or determine if an electrode meets specifications for some industrial or scientific purpose? You're talking radically different qualities of testing.

The way to assay gold for jewelry is to make a streak on a touch plate and then hit it with various acid solutions and see how it reacts relative to known standards. Pure gold doesn't do much unless you hit it with aqua regia, while less pure alloys react in different ways. I don't know the specifics for platinum (or really much more than the basics for gold) but if you want a quick spot check for jewelry purposes I imagine that a test kit of this nature is available.

Platinum and assay are the magic words to throw at Google here.
posted by Kid Charlemagne at 3:52 PM on November 11, 2010

XRF, or, even better, an MS method. I for certain would not trust an Archimedes density measurement (too easy to fake). Chemical acid tests and other kits are semi-quantitative at best unless done under very controlled conditions with certified reagents and techs who know what they're doing.

If you want real, for certain numbers which need to stand up to legal scrutiny, you need an accredited lab. They will almost certainly use an x-ray fluorescence or mass spectrometric method.

If you want to learn how to do it yourself, look into a chemical technologist degree at your local community college, or an undergrad chem degree with a good focus on analytical chem and applied statistics. You then need to follow this up with accreditation by one of the lab standards, such as ISO 17025 (US labs follow different standards, but that's the one the rest of the world is moving towards). Generally, I budget a year to establish and validate a new method. To establish a new QA program in a lab takes 1-2 years, starting from zero. Doing this right takes a lot of care and a very high degree of attention to detail.

If this still interests your, feel free to mail me and I can go into more detail.
posted by bonehead at 6:11 PM on November 11, 2010

something similar to this, maybe?
posted by Glendale at 7:40 PM on November 11, 2010

Where can I go to learn how to verify the authenticity of platinum?

Who wants to know?
posted by platinum at 8:19 PM on November 11, 2010 [1 favorite]

There's a reasonable review of the history of precious heavy metals analysis in this conference report. Current methods are discussed in section 2.3 - Instrumental Methods.
posted by bonehead at 11:29 PM on November 11, 2010

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