These have lots of different names but Google "tiny glass balls" or holeless beads. Ebay has several varieties in different colors but your photo looks like she used clear. http://www.ebay.com/sch/i.html?_kw=tiny+glass+balls. Scrapbookers and other crafters use them. Hope this helps.

Thank you all for the great information.  I was able to find several sources online and got some ordered.

I am interested in finding out where I can get some tiny glass balls (less than a millimeter in size) for firing into an enamel layer.  I asked the artist who made this, but she hasn't replied back.