Hi floor .thx for your report of istanbul bead bazar.I am sure you could find many nice beads in the shops drives.to me your glass piece seems not real old.I am suspect tp patina and crack also.12 years ago I was in Damascu and I saw many copies of ancient glass beads.some seemed also repaired.but I can never be sure about your piece except you show it to some experts.in iran some put beads in bottom part of water cooler to get patina buy salt and other minerals.but surely there are many ways to make patina.now you are a glass bead artist and surely your guess about that piece is very important.news says all syrian antiques were trafficked to three cities in turkey.hope one day they back again to syrian museums.enjoy fish sandwich in Istanbul beach. All the best Ali