Character knits sweaters in amethyst and rust yarn

Please help! I remember a book I read as a child about 25 years ago. It was secondhand and had pages missing and I barely remember anything from it except there was a character who chose wool in amethyst and rust to knit sweaters as gifts for two friends who she was staying with. I think one of the characters was called Joy.
I seem to have had an impression that it was set in America (I am from the UK), possibly Boston?
I know that is basically nothing to go on but I'd love it if anyone has an idea!
Thanks 😊