yes these green and yellow get described as Roman date beads - i don't yet have more exact information... but clearly it seems to me that the necklace you linked to, has been put together by a "designer" using other beads added to create the pattern. so it can't be assumed that this necklace is an authentic roman necklace, but recognisable roman beads are featured in it.
There are "gold-in-glass" spherical beads -which were known to have been made in that era, and then small dark and light faience ring-shaped beads such as were made and used generously in new kingdom Egyptian necklaces in burials ... giving a striped appearance between the featured beads. maybe they were all found together??