Is there a traditional anniversary gift in japanese culture?

[dani]

My friend is having trouble finding something for her japanese sister in law (I am half japanese, so she so wrongly assumes that I'm the expert!). I told her that there is no need for her to give a gift for someone else's anniversary unless it's an anniversary party, but she insists. I suggested a restaurant gift certificate for the couple, but that's not cutting it. Her sister in law had her baby the day before Boy's Day, so my suggestion for that gift was a fish kite, which was a huge hit. Now she wants another japanese gift idea. There are some japanese nurseries nearby, so I suggested a bonsai. We've also thought about an indoor fountain or a watercolor koi painting, but to me these seem more like housewarming gifts. Any suggestions for something more suitable?