spending few days in library, internet and book stores, found alot of interesting stuff about necklaces specifically, this is a short summery:
THE FIRST PIECE: Archaeologists believe the necklace was born during the Stone Age about 40,000 years before than previously believed. April 2004, scientists were excavating a cave in South Africa discovered forty-one mollusks that may have been strung as neck jewelry about 75,000 years ago.
2ND OLDEST: Before this discovery the oldest known necklace to have been found about 30,000 B.C. They are made mostly of shells, bones, stones, animal teeth or claws, strung on a thread.
BEGINNING OF GOLD: In 2500 B.C. gold was starting to be used in neck jewelry, discovered at the Royal Grave of Ur. They are in what is now known as Iraq. 2000 B.C. was when Sumerian bead neck jewelry started to use alternating patterns of colored stones and gemstones and metals such as copper or silver.
GOLD IN GREEK: Alexander the Great in 356 - 323 B.C. conquered the Orient. Gold was plentiful throughout the Greek Empire., which often used on making in necklaces and other types of jewelry for several centuries.
GOLD IN ROME: In Ancient Rome the wearing of jewelry was frowned upon. Laws regulated how much gold could be worn by women or buried along with the dead.
GEMSTONES IN ROME: From about the 1st century on, Roman Jewelry began to distinguish itself. Gemstones came into use and were usually cut in circles or rectangular shapes.
SEXES & ROYALTY: Ancient Egyptian neck jewelry evolved from simple stringed beads to complicated patterns and include the 'broad collar' and pectoral type. They were worn by both sexes, mostly royals and wealthy citizens. They were often buried with their dead owners.
3-DIMENSION: Classical Greek period from about 480 to 300 B.C. most necklaces were 3-dimensional pendants, mostly in the form of heads, seeds, or acorns. They were suspended from a row of flat elements usually some type of rosettes.
MULTIPLE NECKLACES: in the 2nd and 3rd century it became popular to wear multiple necklaces all at the same time. The types of neck jewelry sometimes indicated the level of wealth or class of the wearer. Necklaces were very popular in whatever form could be made. Over the next few centuries the popularity of wearing of necklaces waned significantly. In the late 14th century necklaces started to regain their popularity due to fashions.