In The Merchant Of Venice, what does Leah's ring signify, and does it have anything to do with Portia's or Nerissah's ring?

The rings are the symbol of marriage.  When Portia gives
Bassanio her ring, she charges him not to give it away or lose it.  For her, it
symbolisms her committment and love to Bassanio.

Leah was
Shylock's deceased wife.  For Jessica to give it away for a monkey is a stab in
Shylock's heart since he received it from Leah.  If she had wanted to hurt her father,
she did by this action.  For Shylock it was a precious memeory that she has given
away.

Are the rings related?  In the fact they they are the
symbols of love and marriage, the simple answer is yes they are.