A sphere or even a marble can be a calming way to appreciate the beauty and metaphysics of a stone. The marbles can even be carried in a pocket, worried in the palm of your hand, or slipped into a small medicine bag. Spheres are most often associated with the ability to divine the future, and you would most often want to use a clear Quartz crystal or (perhaps) an Amethyst sphere for that purpose. However, many a sphere that appears to be innocently sitting on a shelf looking beautiful is also serving a dual purpose of attracting positive energies into the environment.
Peachfront Press has a very large collection of spheres, marbles, and even a few eggs. Here are just a few to suggest the possibilities.
Hematite & Pyrite--
The mysterious Louisiana Opal (the mine is now closed)
Ocean Jasper of Madagascar
Malachite--
Red Rutile in Quartz--
Star Rose Quartz--
Ruby & Amber--
Rutile in Quartz--
Very Light Smoky Quartz--