Double sided pendants made from a pair of official Magic the Gathering cards, one for each basic land.
Each pendant is made from 2 basic land cards, one side with the mana symbol, the other with either art from the same card, or the back of another card, showing the circle of the 5 mana colors. Each side has a clear class cover attached which gives it a nice satisfying weight [33g/ 1.2oz for the necklace with it's chain] and the pendant is a bit over a inch in diameter.
The clip version has a swivel that allows it to freely rotate. The inner diameter of the clip is a little less than a half inch, which means it can be clipped on quite a lot of things, including midori and midori style notebooks.