in Dubin's fold-out timeline -it shows spherical glass chequerboard beads in similar colours at nos. 473-474-475 which may have been made and worn between 300BC to 100AD Ptolemaic era , Alexandria, etc.... (sometimes called mosaic but that's a term i don't use because"Mosaic" for me is composed of distinct small glass tesserae usually connected with cement, not fused together.)
these were found in an online local general country house auction sale, at a very low starting price..- nobody else bid anything - may have been deceased effects? the auctioneer didn't recognise them as anything special- described them as "painted"...!!