I don't think she'll mind that you sold her ring -- true, there is an "imprint" on everything she owned, including that ring, but can an object ever replace the spiritual connection you had and still have, even beyond death? (that is pretty much what Beekeeper said)
Keep a picture of her around, light a candle in her memory, those are things she will appreciate.
And don't forget to leave something for your grandchildren when it's your time to go
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