Here is where you can buy glass stands for your spheres. We were excited to buy these as many people did not like the metal stands for their spheres.
I made a video of comparing them and other stands we sell. The plastic and metal stands are here. The clear quartz balls are here.
While the indent will handle under 40mm diameter balls, they seem to hug the 40-50mm best. The glass is not deep enough to hold a sphere securely like the metal stands do. However they do work well at stopping a sphere from rolling off the table. And they show the whole sphere making it look its best. They will not suit eggs at all.