It is an heirloom in the family transferred from the mother to the daughter who is first [to be] married, and so passes to her descendants.
The Wearing of the Ring
The ring worn on the right hand, crown turned inwards tells that the wearers heart is yet unoccupied, the wearer is free as the birds in the sky
The ring worn on the right hand with the crown turned outward reveals love is being considered.
The ring worn on the left hand, place of choice, heart in crown out, she is happily married for evermore
I have read about a a celtic mythological meaning that sayd The Dagda, the father of the gods ,some say, represents the Right hand of the Claddagh ring.
Then there's Danu., the ancestral and universal mother of the Celts, who supposedly represents the Left hand of the Claddagh ring.
The heart represents the hearts of all of mankind...and also represents that element which gives everlasting music to the Gael.
On modern symbolism the Claddagh's distinctive design features two hands clasping a heart, and usually surmounted by a crown. The elements of this symbol are often said to correspond to the qualities of love(the heart), friendship (the hands), and loyalty (the crown).
The expression which was associated with these symbols in the giving of the ring was: "With my two hands I give you my heart, and crown it with my loyalty." Yet, the expression, "Let love and friendship reign forever" can be found as another meaning for the symbols.