Agates belong to the family of chalcedonian quartz. They occur in volcanic areas.
Each colored agate all of which can be found on these bracelets has different properties.
Disclaimer: the following might not be from the highest authority.
For example, blue and green is said to protect one from evil influences. Many traditions view that men gain more attention from women by wearing agates. We can't guarantee that it will be the right type of woman. They say agates increases will power too. There are other things they do but we don't want to go overboard here.