Back in the last century (that sounds so long ago - I'm talking about the 1990's), lots of gardens had gazing balls. I don't know if that's the case now. In the last few years, I've been on several garden tours, but I don't recall seeing any of the colorful balls that you used to see, oftentimes in funky gardens (but not always; the above garden is anything but funky).
I think this is one of those garden ornaments that goes in and out of vogue. The Victorians used them extensively. Known also as witch's balls (to ward off witches that might come to your front door; apparently witches couldn't look at images of themselves) and garden globes, the gazing ball dates back to pre-Renaissance times in Italy. It's been in gardens ever since, and while there may be a slight lull in their popularity, there's no shortage of places to buy them currently (Amazon and Walmart.com even have them for sale).
One of my favorite uses of a garden globe was by a Dayton, Ohio, gardener. She had placed a ball covered in different shades of blue mosaic pieces on the ground in her perennial bed. Growing around it was Geranium 'Rozanne', a beautiful blue flower that blended wonderfully with the colors on the sphere. Another great combination was in a country garden outside Chapel Hill, N.C. A bright red reflective ball stood on a pedestal surrounded by the light purple Aster tataricus.
The above photograph was taken in Bernadine Richard's expansive garden in Sandy Springs, Georgia. There's something very whimsical about that blue ball floating among the water lilies. Gazing balls were also called Globes of Happiness. I like this moniker best. It seems fitting for the above scene, which brings a little cool to this hot August day.