By-the-way ykhuser the amulet which you are asking for in the other forum, the first one is luang phor thuad. This is an amulet that commemorate the monk by the same name. He is known to have help people from harm and sickness about 100 year ago. So depending on the chant that is recited on the powder before it made into an amulet, it has different applications. But mostly help to prevent sickness, this is because back then medical are not so advance and people tend to rely on religion to cast out evil sickness deities or something.
And as for the other stone like thing which you have shown, I have no idea. Again in most cases the amulets are done by each temple to commemorate a certain monks or deities. And it is very much depending on what sort of material for the powder and the type of chant they have recited into the powder. Also depends on how long did the monk or monks chant into the powder before making into an amulet. Therefore the effect will have different results. Same goes with the stone which you have feature in the other forum.