Handmade Gifts: Costume Jewellery

I don't usually make jewellery but made this necklace for my sister in law's birthday!  It was enjoyable making something completely different than my usual sewing.  All the findings were from different places around the web and you can see in the photo below the 'antique' colour has rubbed off the jump ring holding all the leaves and flowers together?  Any suggestions on how to avoid this?

The leaves are intended for a few hair pieces too!