Dating jewelry accurately can be quite a challenge. Many materials and techniques used today in production are the same basic methods used for at least 5000 years! Crafts people today take gold, silver, and other metals, and use the techniques of granulation, casting, engraving, chasing, and piercing to produce beautiful jewelry, just like the metal smiths of Ancient Egypt and Asia Minor did ages ago.
While most contemporary and vintage jewelry is marked, and gives us a great basis for dating a piece, there are many unmarked beauties out there that require a little detective work to uncover the date of production. The metals used often give us some great clues.
PRECIOUS METALS
Most antique fine jewelry is made from yellow karat gold or silver. The majority of pieces made before the mid-19th century will be European, which includes Great Britain and Russia.
The practice of hallmarking jewelry and objects made of precious metal started in the 1400's and continues to the present. Even so, many unmarked pieces exist. Not everyone hallmarked their work, and the passage of time and repair work has marred or eliminated many marks.
Some antique pieces, constructed from yellow gold, have silver work added, often in areas where stones are set. Because yellow gold imparts a yellowish tint to colorless stones when used for setting, adding silver minimizes the effect. Due to its' characteristics, silver is not as durable a material for some items as gold. The 19<SUP>th century brought with it the development of torches with sufficient heat to melt platinum allowing jewelers to use white metals for the body of a piece.
PLATINUM
The ability to use platinum in the production of jewelry allowed for the development of new styles of jewelry in the 1880's. Platinum is a strong metal giving jewelers of the time the ability to create elaborate filigree and openwork, styles we most often associate with the Edwardian era. Platinum is used in its alloy form, with a traditional purity of 90-95%. Iridium is usually the other material used in the alloy.
Platinum was popular from its first usage until about WWII. Wartime restrictions limited its' use. Palladium, a platinum family metal, is used in some pieces from this period, often in an alloy that included iridium. Platinum, while used after WWII, did not regain widespread popularity until the 1990's.
WHITE GOLD
White gold is the newest alloy that you will see in pieces described as antique. Various sources date this alloy to 1911, 1915, and 1917. Earlier attempts to produce a white gold alloy were unsuccessful. The alloy is normally a mix of metals, with nickel providing the white color. Some nickel free alloys exist that incorporate metals from the platinum family to obtain a white color. Some white gold alloys tend to have a yellowish cast, especially the nickel alloy white gold, and pieces are often rhodium plated to produce a shiner, whiter piece. Some white gold is relatively brittle due to the presence of nickel, which causes a loss of malleability and ductility. Care should be taken when repairing items made from white gold and nickel because defects can occur if the metal is not treated properly. When examining an older pieces make an extra effort to find any defects, especially look for prong damage and tiny "stress" cracks.
Many credit the Belaise Brothers with the invention of white gold, or at least the first successful marketing of white gold. The terms Belaise metal and white gold were synonymous in the 1920's. There are collectors that are thrilled to acquire an early 20th century piece with the Belaise hallmark.
Describing a white gold piece as Victorian is incorrect, and the use of the term Edwardian is questionable, since the Edwardian Era ended in 1910.
The rhodium plating which is used to improve the appearance of white gold can also be used to deceive. Some manufacturers will make a piece in all yellow gold, and then rhodium plate some areas to give it a two-tone look, giving the piece the appearance of being made from yellow and white gold. For decades manufactures have used this process on the prongs of a piece. When white jewelry, including platinum, made a strong comeback in the 1990's, some manufacturers simply started plating yellow gold rings with rhodium. This finish will not hold up to daily wear in an item such as a ring, and will not survive some types of repair work.
OTHER METALS
For as long as gold and silver have been used in the production of jewelry, someone has been trying to duplicate the look with something less expensive. In some cases it is an honest effor, but in others the intent of the parties involved are less then honorable.
Brass, an alloy of copper and zinc, is probably the most common substitute for gold in older pieces. There are some very nice antique 'Bohemian Garnet' pieces set in brass. Pieces, such as these, are also made in low karat gold alloys and with quality karat gold settings, so all merit a careful examination.
The most famous of the copper and zinc alloys used in jewelry is Pinchbeck, developed by Christopher Pinchbeck, a London watchmaker, at the start of the 18th century. Pinchbeck, and similar alloys, were used in jewelry until being replaced by electroplated materials in the 19th century. These alloys, sometimes called gilding metal, are still used as a base for plating. The brassy or copper-like finish is often visible on items where the plating or filled finish has worn away over time.
Coating items with gold was practiced in France in the 1700's. This gilt work involved the use of very hazardous materials, and died out, along with many of the gilders. Electroplating of base metals with gold and silver developed in the early 19th century. Birmingham England, which had been rather famous for its production of shoddy jewelry and other accessories, became the center of this trade. The electroplating process soon displaced Sheffield plate in traditional silver items, and electroplating was adaptable to small jewelry objects, which was not the case with the Sheffield process. Birmingham was the right place and the right time to take advantage of all the innovations of the Industrial Revolution.
Gold plating or gilding over silver, or vermeil, was used in the early 19th century. It was infrequently used after that, until the mid 20th century.
COPPER
Copper has been used in jewelry, but is not under stamping requirements, as most materials made of precious metal or having a precious metal finish are. Copper saw a good deal of use in the Arts & Crafts Period. It was used by modernist 20th century jewelers such as Francisco Rebajes, and then by companies such as Renoir/Matisse. It is also seen in some Southwestern and Mexican pieces.
If a seller makes a claim in a listing that a piece is composed of precious metal, they must show the quality mark. If there is no legible quality mark, the item must be tested and the test results must be included in the listing.
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PLATINUM
WHITE GOLD
OTHER METALS
The most famous of the copper and zinc alloys used in jewelry is Pinchbeck, developed by Christopher Pinchbeck, a London watchmaker, at the start of the 18th century. Pinchbeck, and similar alloys, were used in jewelry until being replaced by electroplated materials in the 19th century. These alloys, sometimes called gilding metal, are still used as a base for plating. The brassy or copper-like finish is often visible on items where the plating or filled finish has worn away over time.
COPPER
