My first favorite thing was a Christmas gift by my sister-in-law, April! And it's by far one of my favorite Christmas gifts from this year. I have gotten so many complements and questions about it since I started wearing it. The way it works is you buy the ring and with the ring comes about 10-15 interchangeable marbles. Decide which marble coordinates with your outfit, place the marble in the ring and then it's ready to wear.
My ring is from Got All Your Marbles and it's the Pee Wee Lotus Ring. The price isn't bad ($56) considering you are getting like 10 rings in one. If you aren't a fan of rings there are necklaces and earrings available as well.
You can also order additional marbles. I just order a few from Trendy Stone Jewelry. These semi-precious stones range in price from $3 - $50. I recently just ordered an Amber stone (which both my sisters-in-law say is a must have), a Green Adventurine stone, and a Red Jade.