One of my favorite Irish symbols is the Claddagh. I was going to explain it, but Wikipedia already did so in such an informative, neat and concise way that it was easier to just cut and paste:
The way that a Claddagh ring is worn on the hand is usually intended to convey the wearer's romantic availability, or lack thereof. The ring is worn on the right hand with the heart facing outward to show that the wearer is not romantically linked but is looking for love. When turned inwards, it is shown that the wearer is in a relationship, or their heart has been "captured". Noting that the heart is pointing down the hand and into the veins which lead to the wearer's heart. The ring worn on the left hand with the heart facing outward shows the wearer is engaged; turned inward indicates the wearer is married.
Isn't that sweet?! Here are some of my favorites from good old etsy! :)
Images link to the product pages.