Platinum alloys

Hello

I want to make some platinum rings but the only alloy that seems to be available in the U.K. from Cooksongold etc is PT950/cu.
my only previous experience of platinum was in the US where the harder and more expensive PT950/ru seems to be the norm.

I have done google searches but not found a great deal, so thought there were likely people on here that had used the bullion from Cooksons and would be able to answer a couple of questions I have.

How was it to work with?
How is the colour?
Did it polish easily?
How resistant was it to damage or tarnish after a few months of use?

Thanks
Darren