The eternal knot (above) represents how everything is connected. The eternal knot can be found on a necklace or on a bracelet.
The lotus flower (above) symbolizes the true nature of all mankind. The lotus flower can be found engraved in a ring.
The dharma wheel (above) illustrates Buddha himself. The dharma wheel is also called the dharma chakra or the dhamma chakka. It has became the sign of Buddhism. Did you know, that the eight pegs on the dharma wheel represent the Eightfold path?