What can I use to get a really clear shade of blue in my vase (so it looks like blue ocean water)? natural?

my centerpiece idea:


fish bowl, with floating flower, %26amp; clear blue water


what else can I add to my bowl? I can only think of rocks, but is there anything shinny I can add also?


Thanks for the help!What can I use to get a really clear shade of blue in my vase (so it looks like blue ocean water)? natural?
Food coloring should work for the blue color. You could also add marbles or beach glass (from a craft store) and shells.What can I use to get a really clear shade of blue in my vase (so it looks like blue ocean water)? natural?
you can use blue food coloring to color the water, you could us coins , or marbles they also make different colored glass bead,that you could use , should be able to find them in your hobby and decorating stores like hobby lobby, and pottery barn.