A hallmark is an indication that the metal you are receiving is what the seller says it is. It is your guarantee that you are getting what you think you are getting.

Above is an example of how my pieces are hallmarked.

Do you know how to read a hallmark ?

 Starting from the left the first symbol is the makers or sponsors mark. 

The next two indicate which metal has been used (the fineness mark). 

The next one (in this case the leopards head) shows where the piece was hallmarked (London).

The letter at the end shows the year it was marked. 

So… Who, What, Where, When. 

I love learning about this kind of thing, hope this has got your mind dancing!