51 beads ranging from small to large.
Thank you for submitting your item for appraisal. This appears to be a so called african trade beads necklace, an old 1920s imitation of amber, basically a kind of plastic, specifically phenolic resin. Such beads were produced to be used as a currency in remote African countries or they found their way there by trade. Phenol formaldehyde resins were invented in the 1910s and resurfaced as imports from Africa in the 1960s in Europe and the US. The estimate is based on similar sold at auction. Asking prices in the trade are higher and can vary.
For further reading I would highly recommend this article: http://beadcollector.net/articles/Beads_28_Phenolic.pdf