Seeing your mother’s hands all those years wearing the rings evokes a lot of sentimental feelings in some people. It is rarely about the actual value of the piece but the value the owner put on it in their lifetime.
How about suggesting to them that they make a replica using some of the gems in each one, so that each ring has part of the original, and they split the cost equally?
I am the eldest daughter and my mother has very clearly said she want me to have all her jewellery. Not sure how I really feel about it as I wear my grandmothers jewellery already and have my MIL’s in a box. My MIL left a detailed list of what she wanted each female family member to get, and we spent several nights trying to figure it out but it was not at all clear which item she was describing. In the end each family member took what they preferred rather than follow the list.