Platinum chain Pt950 question about alloy

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I’m going to leave this here because I’m embarrassed to ask in Rocky Talky.

Does anyone know about platinum chains? I want to buy a PRE-OWNED platinum Iridium chain, not a platinum ruthenium chain.

I’m looking at used platinum chains on EBay.

If a chain from Italy says Pt950, should I assume it’s using Ruthenium alloy?
If a chain from Jared’s says Pt950 should I assume it’s Ruthenium alloy?
Is there any way I can identify a platinum Iridium alloy blend by the marking or by testing the metal?

Backstory
I recently tried for many months to find a used Iridium Platinum ring setting but it seems like PT900 is not really available any more, even in used items. So I’m assuming that chains are no different.

It seems like the entire world has switched to other alternate alloys, the predominant one in the US being Ruthenium.

I DONT WANT Ruthenium. I have a confirmed sensitivity to Ruthenium. I try to resist the switch to Ruthenium in the industry because the metal is so toxic for metal workers. And, I personally hate the blackish tone of Ruthenium platinum alloy and the extreme hardness, vs Iridium platinum which is whiter and feels softer almost like sterling.

Can anyone tell me to how to find and identify a platinum Iridium chain?

 

[Karl_K]

plat 950 in chains is more likely to be platinum cobalt as plat/ru.
The biggest problem is the pre-owned. The vast majority of people have no idea of what alloy was used and where it is from doesn't help because it can change over time.