As I have remarked many times (often here), these very nice beads are post-Roman Period, from the Byzantine or Early Islamic Periods—which we can tell by the cane patterns that include external stripes.
I have seen three or four of these necklaces, including in the Liese and Lindstrom Collections. They sometimes include reworked elements that I surmise are probably recycled from broken beads (or other sorts of pieces).
Just a word of caution - I've bought from TimeLine Auctions before and the beads turned out to be modern copies. They looked good online, but not so much in person. I'm sure they sell some real stuff too, but my sense is they have a lot of fakes mixed in.
In the present instance, I think it is possible to say there are no convincing reproductions of this material.
The only way an imitation would be received would be if the necklace were switched with something else.
Nevertheless, in the past year or so there have been some editions of similar beads from Java, that are (of course) being misrepresented as "ancient." However, they are under my radar because they are visually different from the beads they attempt to copy. Plus, there are multiple numbers of the same beads (in a strand)—which is not a common finding among bazaar strands and made-up necklaces of ancient beads, such as we have here. This (matched strands) is what we see when new editions of beads come out of current factory situations. Down the road, someone may TRY to copy the look of the present necklace (and those I have documented already). But I am reasonably confident it has not happened yet.