Check out page 21 of the card images on the BCN articles page link to the Picard's early 20th century Conterie cards. I assume these are from the Societa Veneziana per l'Industria dell Conterie (Venetian Society for the Glass Bead Industry) but I don't know if they had specific dates indicated anywhere. The Societa was founded in 1899.

In Middle Eastern and Venetian Glass Beads, by Panini, the version of the bead with the plain blue bow tie is shown on p. 200, and attributed to the first half of the 19th century and Dubin's The History of Beads (1988) is the reference.