Can anyone tell me what this symbol is or stands for?
Thanks!

Is the symbol on the back kanji? I can't quite make it out. You might do better to take a careful rubbing of it and post that.

Whatever it is, it's pretty.

I can't tell what is on the back. The pin is the size of a dime.

Try taking a rubbing and enlarging it, if possible.

My guess is that the mark is a maker's mark. If it is kanji, or another asian script, it might at least give a country of origin.