Make the gift personal - personalised mugs or a photo frame; of put together a photo album of the last year with photos of them in it (this may take forward planning during the year) plus photos or news clippings of happenings that have taken place that year. A hand-made piece of pottery or a painting by an artist that they love will be treasured.
Celebrating with your friends when they have reached another milestone year in their marriage is a great experience and something you want to make as special as possible with the perfect gift. The gift you choose could probably depend on how many years they have been married. Traditionally, each year signifies a certain element or token, for example one year is paper, two years is cotton, three years is leather, four years is fruit or flowers, five years is wood, ten years is aluminum or tin, fifteen is crystal, twenty is china, and twenty-five is silver. Or you may want to get them something else which you know they would both enjoy.