Position the stalk of a single synthetic flower in the center of a clear, wide-top vase; then fill the vase to the top with a selection of pebbles of different colors, sizes and textures. Cut the petals from another flower the same as the first and sprinkle a few over the pebbles at the top of the vase. This simple arrangement creates a contrast between the delicacy of the flower petals and the hardness of the pebbles, and makes an interesting centerpiece.
Line the base of a square glass vase with pebbles of roughly the same size, shape and color. Nestle a round candle into the pebbles and tie a thick silk ribbon around the outside of the vase. Choose similar colors for the pebbles, candle and ribbon for a coordinated look that complements your color scheme.
Select five or six flat pebbles that vary in size and stack them on top of each other from largest to smallest. Glue them in place with craft glue and leave to set. Add some glue to the base of the bottom pebble and carefully lower the stack into the center of a large square vase. Leave the vase plain or paint a pebble motif in a strip around the outside using white glass paint. This decoration would look good in a bathroom, and it draws attention to the hard edges of the square vase and smoothness of the pebbles.