okay, here is what my husband said:
it is a ground /dig find, glass is of different composition, that's why the yellow and white look in most places like new and even shiny. The brown spots should be sinter, the soil the bead was deposited in caused some etching. The large round spotted structure on the black glass in the first picture looks a bit strange. All the "marks" on the bead depend on how the bead was deposited in the soil. His gut feeling says it is genuine old. You know yourself that it is difficult to judge only from pictures, better to have the item of interest in your hand. Pictures are bad, before buying he would ask for better pictures. Given that Islamic Near / Middle East currently is the world's most important and best region for tomb raiding and illicit digging, does support the gut feeling. We learn from our media how easy and excellently organized it is to sell such finds from the first one who dug (poor peasant or similar) to worldwide. This is no judgement about the bead as type, age, etc

If I were the seller, I would at least add some description - would be easier to sell, it does cost a bit more than few $

Brigitte