A Moonglow is a modern glass button, opaque or translucent in color.  A  layer of clear glass molded over the top produces the vacillating "eye" in the glass.  Some medium Czech moonglows do not have such an "eye".  Moonglows were made in many
different patterns, colors and finishes.

Beginning around 1953 and into the 1960's, they were exported from Western Germany and
Czechoslovakia. But despite the vast quantities that were produced, some are quite rare.

There is at least one known with metal OME (Other Material Embellishment).  They frequently have sparkling stones, sometimes as many as 14.  Moonglows
with 2 or 4 stones are more rare.

Usually they have a self-shank, but there are some 2-hole sew-throughs.  A few 4-way box shanks in the larger sizes and even a rosette shank have been found.  The metal-shanked Moonglows are  believed to have been made in
Czechoslovakia before WW II.

BACK MARKS are classified as verbal and non-verbal. 
Verbal: Le Chic, La Mode, Costumakers, S.H.B.C., B.G.E., B.G.E ORIG., Modella, and Ges Cesch.
Non Verbal: eight spokes, ten balls around the edge, compass spokes, two dots at the edge, fifteen star points around a convex button.
Not all Moonglows are backmarked.

There are many Moonglow shapes, realistics and finishes.  There are even transfers and painted ones. Here are two very scarce carmel clock and green telephone Moonglows.