Info found on Etsy, from a Japanese seller named MiyabiGrace:

"It is said that the cotton pearl jewelries appeared around in the middle of 19 century. During Art Deco era, many layers of pearl necklace style were booming, however, the weight of those jewelries was so heavy. Therefore, in order to lighten the weight, the cotton pearl beads were invented.

　　Cotton pearl beads had been manufactured until around in 1955; however, due to the popularity of plastic pearl jewelries, cotton pearl jewelries disappeared from the market. Recently beautiful antique-like and lustrous cotton pearl jewelries are booming in Japan. So the beads has been manufactured again since 2009. There is only one manufacturer in Japan and these cotton pearls are rare pearls in the world."