Smallest bead 1 x 1 mm and the largest bead is 6 by 7 mm. Length of the chain is 55 cm.
The British Museum has almost identical small glass beads from Zanzibar. These ancient beads were found in Zanzibar / Pemba during the the early 1900's and donated to the British Museum. The British Museum identifies the origin of most of the glass beads as probably being from Persia (Iran) See the slide-show for comparable beads in the BM. The book by F.B. Pearce (see below) gives more details about the beads that could be found around Zanzibar during the early 1900's.It should be noted that before the arrival of the Portuguese the trade with Arabia was run by the Kingdom of Hormuz (1000-1500). This kingdom was run by Persians (Shirazzi?) en Omani Arabs.
A recent scientific study (ref 2) by Marilee Wood etc. Zanzibar and Indian Ocean trade in the first millennium CE: the glass bead evidence concludes that some of the glass beads found on Zanzibar Island (Unguja Ukuu and Fukuchani) are several thousand years old, while others are from a later period but also many centuries old. Many beads may originate from South and South-East Asia. Glass Beads were not completely made in Zanzibar however evidence was found that glass tubes were imported and locally converted into beads. See also the Slide-show for a photo of these beads (copied from this paper) Our beads look very similar but not sure they are also that old.
F.B. Pearce writes in 1919 (ref 1) : "Besides Carnelian beads , pierced amethysts and garnets and great quantities of glass beads are also found at certain states of the tide at the ruined towns in Pemba. They are generally considered to be of Arabian or Persian manufacture, and date from the twelfth to the fifteenth century; although some specimens may be considerably older and date from the Ptolemaic period. The most common bead found at Ndagoni is a large, irregularly shaped bluish-green glass bead of a distinctive character. After heavy rain they may be picked up by hundreds. That they are of somewhat archaic manufacture is evident from the irregularity of their shape ans size. Many appear to have become distorted in the process of being made. The question is often asked how the existence of such quantities of beads in the sea-sands of Pemba can be accounted for:
1) That they formed part of a cargo of a wrecked ancient ship
2) That they have been washed out of ancient graves by the encroaching sea.
3) That they are the remains of some propitiatory or thank -offering made by the former inhabitants of the ruins, to the sea
4) that a bead factory factory or depot existed at the towns where beads are now found and that the encroaching sea has liberated the beads.
The fourth explanation seems the most probable . It is worth noting that at Mogishu in Italian Somali-land one of the oldest Persian or Arab settlements on the coast, complete apparatus for the manufacture of glass beads, glass stems, and coloured beads has been found (see Justus Strandes Die Portugiesenzeit von Deutsch und English Ostafrika). If a glass-bead manufacture existed at Mogdishu there is no reason why similar establishments should not have been erected elsewhere in the region" e.g. page
The necklace section contains a long chain with antique silver, wooden and ancient glass beads.