Difference between 90% platinum and 95% platinum

[dazed_and_confused]

Hi,

I need help with platinum settings and I''m having a hard time understanding what is the "best" in the long run.

I did a search on pricescope and my understanding is 90/10 will give the best overall quality and durability.

For 95/5 platinum settings, there seems to be many variations that contain Cobalt, Iridium, or ruthenium.

I have several questions...
1. What does the 90/10 setting contain: Cobalt, Iridium, or ruthenium?
2. If 90/10 is not pure as 95/5 in terms of platinum, then how come price differences seem to be minimal? I checked a few stores in NYC area, and it''s about $200 price difference.
3. Why would you rather select a 90/10 over 95/5?
4. If you''re in a store looking at platinum settings, how can you be sure 90/10 or 95/5 setting contains one of the Cobalt, Iridium, or ruthenium. It''s not like they have a report for diamonds where they say this settings contains this much amount of metal.
5. In a platinum setting, is hard or softer better? I know harder is more resistant to scratches...but why would you go for softer?

Thanks in advance for any help provided!

 

[Avplayer]

this should help

http://www.mwmjewelry.com/platinum_purity.htm