p10ker

I have been having all sorts of problems trying to find the (COR) of various materials. I am specifically interested in materials that can be used in a Newtons Cradle. Steel seems to be the most commonly used and this has a COR of around 0.9 and I was just wondering if glass or something else has a higher value. Diamond may well have a higher (COR) (does it?) but obviously this is too expensive. Any semi precious stones or synthetic precious might be affordable. Matweb doesn't list (COR) as one of its properties which is a shame as this site would be ideal to use. The balls will be about 50mm in size and they will be pulled out about 50mm from the side before being released so no unusually large forces will be acting on the balls. So, anyone got any suggestions of what materials might be viable rather than steel? Any sites out there that I don't know about that lists the (COR) of various materials? Thanks for your time, G