My friend Di bought these coloured glass buttons recently at the Miyuki Seedbead Co. in Tokyo, Japan. She was led to believe that they were made there.
They resemble the lacy glass buttons I have seen in button books. They are clear glass with different colours painted on them and finally a coat of black paint on the back. They also have some gold lustre on the front. One has a four way box shank, the other a loop. They measure 2 1/2cm.