Help to find out what this is....

Does anyone know what this is? I've searched and searched and haven't found anything :(

you have image of Mexican 8 reales stamped on medalion.

N#3767

It appears to be a cast replica of that coin, made in to a coin dish, which has been made into a pendant.

There are very many of these coin-bowls or coin-dishes, from various countries. 

They seem to be associated with weddings, but I did not research very far, further research using le Google is up to you.

  Not sure if these are true, but also heard . This would be used for baptism cups. Or a rich person water cup. Ware around neck so if they can get a cup of water out of public wells or fountains.