Ooops, I forgot to link to the ad.
http://prodavalnik.com/trsya-stkleni-topcheta-limki-kato-tezi-ot-snimkite-ot-edno-vreme-sots-vreme-imashe-gi-vsyako-srelbische-i7688737
The description on the photo(s) in that ad translated to:
LOOKING GLASS BALLS LIMKI made in Sliven OF FURNACE FROM ONE TIME DURING SOC
Wiki says Sliven is the 8th largest city in Bulgaria. What might "SOC" be? [Edit: Looks like Socialist era ... 1946 to 1990?]
[Next edit: Limki is apparently a Bulgarian marble game (link) and might also be the name used for the marbles themselves (link) ]