1. Be made of rare materials difficult to obtain
2. Be made of precious metals like gold / platinum / silver etc
3. Last a long time before physical degradation of material sets in
4. Be made by unique processes of combining different materials
5. Be made of certain materials which are expensive in raw form

A very high rating in the Materials category would imply almost all of the above. Items with ratings in the middle range would have some of these qualities.These ratings although apparently subjective have been set according to certain conditions. These conditions are continuously evaluated according to user feedback to make these ratings more meaningful. If you want to know more about these ratings or offer feedback please use the Contact Us page.