Silver plated / Rhodium?

[Ohiogoldfever]

Over the last several all years I have been collecting silver plate that I can come across super cheap or free. I have about 100lbs of misc platters silverware and the like.

It all tarnishes at about the same rate besides a few pieces I found the other day while organizing things. I have a few platters that are super bright, very clean and silver white looking despite them being with a ton of other tarnished material.

Any shot these may be plated with rhodium?

 

[nickvc]

I think it highly unlikely but they could be coated with a similar covering you get on that cheap gold plated chain on rolls, if so it’s a pain to remove….

 

[orvi]

If the base metal is stainless steel or any ferrous material:
Cut a piece of suspected "rhodium" plated ware, mix some dilute (battery acid is OK) sulfuric acid with small ammount of nitric acid and throw the test piece in.
All base metal will start to dissolve, except the rhodium. Which if it is present will flake off as shiny foils.
If it is silver coated with some resin/lacquer/epoxy, you will clearly see as it will dissolve.

If the base metal is some copper/brass etc. than plain nitric would be sufficient to test.

Rhodium is used mainly for plating jewelerry.
If you have possibility to check on XRF somewhere for free or little charge, go with XRF.

 

[Alondro]

If the base metal is stainless steel or any ferrous material:
Cut a piece of suspected "rhodium" plated ware, mix some dilute (battery acid is OK) sulfuric acid with small ammount of nitric acid and throw the test piece in.
All base metal will start to dissolve, except the rhodium. Which if it is present will flake off as shiny foils.
If it is silver coated with some resin/lacquer/epoxy, you will clearly see as it will dissolve.

If the base metal is some copper/brass etc. than plain nitric would be sufficient to test.

Rhodium is used mainly for plating jewelerry.
If you have possibility to check on XRF somewhere for free or little charge, go with XRF.

I have a mysterious piece of jewelry that looked like silver, had no identifying marks. I assumed it was silver plate and so tossed it in with some silver to refine, but it was totally resistant to plain nitric acid, and even aqua regia barely touched it.

Heating it partly dissolved it in AR, but when it cooled, the metal fell back out as a grey powder, completely coming out of solution.

Am I looking at a platinum chain here, or a platinum rhodium alloy?