Can't help thinking you'd get more posts if you'd titled this thread 'Antique Christmas balls' but you might not have liked the majority of comments!

Good luck with your searches... try searching 'baubles' as one of your key words. Any indication where they were made? Germany was the epicentre for all glass Christmas tree ornaments at one time - as is bourne out by the multitude of Christmas shops open and trading well in August!

LTS