Check out the web pages of engine and plug companies.

I found multiple references to platnum in glow plugs easily.

http://www2.towerhobbies.com/cgi-bin...?&I=LXG899&P=7
http://www.mecoa.com/faq/glowplug/glowplug.html
http://www.osengines.com/faq/faq-q663.html

And that was just a couple of quick ones.