A bell jar or cloche glass can be very attractive with a small fern or little grouping of plants or mosses underneath it. It's come into fashion right now, so often buying them new can be expensive.
But, you can find them second hand, or even make your own from large, attractive glass jars. Just make sure that if you are buying them to put plants underneath that you don't try to be too wild with the glass.
The plants may not survive or thrive under certain kinds of colored glass as they need a wide spectrum of light for photosynthesis. Just use clear glass, if you are in doubt.