Here are 20 antique Czech, glass buttons! They are oval in shape, blackish-blue-purple colored, and iridescent! I think the glass is dark blue or black though the purple, blue, and green colors are very vivid and bright so that's mostly what you see.
They measure 3/4" long X 1/2" wide approx.; they have glass shanks.
These remind me of little shiny iridescent beetles!
CONDITION: These are in very nice antique condition.
Let me know if you have any questions!