Dating jewellery comes from a combination of pieces of knowledge. One has to consider the style of the piece; the faceting pattern or cutting of any stones that are present; the metal standard in relation to the country of origin (together with any hallmarks or maker's marks); the overall construction and particularly the technology and patent dates for things like pins, clasps, jump-rings; and a bunch of other things too.
Glass has been used as a substitute for natural gemstones for hundreds of years: both as an honest way of providing flashy jewellery for those who couldn’t afford the real thing; and as a dishonest way of duping those who thought they were buying the real thing.
By the 11th Century it was in such wide use that the Guild of Goldsmiths in France tried to protect the reputation of its members by dictating that gold should only be used as the setting for natural gems; and glass should only be set in silver. Venice in Italy was one of the major producers and exporters of glass imitation gemstones. The Senate there also tried to protect the city’s reputation in 1487 by forbidding the production of imitation diamond, rubies, emeralds, sapphires and a range of imitation semi-precious stones.
Early glass was moulded, often had small bubbles in it, and lacked the sparkle of natural gemstones but that changed in 1675 with the development of high-lead content flint glass by George Ravenscroft in Britain. A further and more dramatic improvement came in 1724 when the French jeweller Georges Frédéric Strass developed a material that came to be known as ‘paste’, ‘diamante’ or ‘strass’… a leaded glass that could be cut and polished with metal powder to an appearance very close to diamonds. It remained popular through to the 19th Century.
Then, at the end of the 19th Century the Austrian jeweller Daniel Swarovski, introduced high-lead cut-glass crystals as diamond imitations and then coloured versions to imitate other gemstones. In 1892 he also patented a mechanical glass cutter so they could be mass-produced to satisfy the ever-increasing demand.
