One of the most-often-asked questions about antique and period jewelry is its age. Part of the “job description” for someone who studies, buys and/or sells old jewelry is the ability to contextualize a jewel with the period in which it was made.

History may not have been your favorite subject in school. But anyone who handles antique and period jewelry has a good reason to remember dates. Knowing when metalworking and manufacturing techniques came about, when patents were issued for jewelry findings and when certain gemstones were discovered can help us to circa-date a piece and, thus, become better at what we do.

What follows is a compilation of dates taken from the timeline of my book, Warman’s Jewelry, and from subsequent research about jewelry-related technology from the 19th and 20th centuries. To make this chronology easier to understand and remember, the dates are grouped by topic rather than chronological order as they are in the book’s timeline.

A simple listing of dates isn’t enough, however, because dates of historical events are subject to interpretation. It’s equally important to know what conclusions can and cannot be drawn from them. Dates of inventions and discoveries can help circa-date a piece of jewelry to the earliest possible year it could have been made, but the latest possible date may still be open to question. Other mitigating factors that require further explanation often come into play. Therefore, specific dates for specific events are given in boldface within their explanatory paragraphs. These dates should be noted as indicators of subsequent developments in jewelry-making that evolved over time.

The dates are as accurate as I could ascertain, but conflicting sources are common. This is when the word circa (or approximately) comes in handy.

METALS & METALWORKING TECHNIQUES

The use and designation of precious metals has changed considerably in the past 200 years. Aluminum, when it was first successfully extracted from its native clay in 1854, was considered a precious metal. But platinum didn’t achieve precious-metal status until the end of the 19th century, well over 100 years after it was first put to use.

Gold has been valued for its unique properties since ancient times. However, techniques for making gold jewelry have changed. In the early 19th century, gold was in relatively short supply, so settings were open and lightweight. A type of filigree called cannetille – a favorite decorative technique of the 1810s, 1820s and 1830s – made a small amount of gold go a long way. The California Gold Rush of 1849, followed by gold discoveries in Australia in 1851, the Black Hills of the Dakota Territory in 1874, South Africa in 1886 and Alaska in 1898 ensured a more plentiful supply of gold for the rest of the century.

By the 1840s, filigree was out and repoussage was in, whether executed by hand in expensively wrought jewels or stamped out by machine in less costly pieces. The Industrial Revolution was well under way by the early Victorian period, and die-stamping became the predominant mass-production method for the manufacture of jewelry for the next 90 years. Surprisingly, it wasn’t until the 1930s that factories turned to a new application of the ancient art of lost-wax casting. Multiple copies of one design were made possible with the aid of vulcanized rubber molds (using the vulcanization process that Charles Goodyear patented in 1844; see “Other Synthetic Jewelry Materials,” page 166), along with the development of an improved casting investment plaster in 1932.

The 1840s also saw the development of two techniques that would prove vitally important to the manufacture of inexpensive jewelry, which was beginning on a large scale in the U.S. and was already well under way in Birmingham, England. The first technique was electroplating, developed and patented in 1840 by the Elkingtons of Birmingham. The deposition of precious metal onto base metal using a direct electrical current was cheaper and much less dangerous than the age-old process of mercury gilding, though not as durable.

The second important process was rolled goldplating, brought to the U.S. from Great Britain in 1848. It was a big hit with New England jewelry manufacturers. Unlike electroplating, which is applied to a finished base metal article, rolled gold is a mechanical process for sheet and wire that is then used to manufacture a finished piece. The technique was derived from Sheffield plate, developed more than a century earlier, which is copper clad with silver and rolled to the desired thickness. Rolled gold is copper or brass clad with gold, also known as “gold-filled” in the United States. The metal “sandwich” was treated exactly the same as karat gold – stamped, engraved and fashioned into pieces that were identical in appearance to their solid gold counterparts. The French began to use the technique in the 1820s, calling it doublé d’or.

Hallmarks on metal are invaluable dating tools. The British have hallmarked gold and silver for centuries. The British system of date letters eliminates the guesswork of circa-dating, but they are not always used on jewelry (see Myra Waller’s article, “English Jewelry Marks,” Heritage, August 1990). The karat designation on gold by itself will yield some information, however. In 1854, the legal karatage of gold in Great Britain was lowered to allow the use of 9k, 12k and 15k in addition to 18k and 22k (note that in Britain, karat is spelled “carat,” and the abbreviation is “c” or “ct”). Then in 1932, 12k and 15k were eliminated in favor of 14k.

In the U.S., the requirements for marking gold were established in the National Stamping Act of 1906. The act also raised the sterling silver standard from 900 to 925, but several U.S. companies used sterling silver well before 1906 and voluntarily marked their wares so the date isn’t as useful for pieces marked “sterling.” But the mark “standard” or “coin” on a piece of U.S. silver jewelry indicates pre-1906 manufacture.

Like the British, the French have hallmarked gold and silver since the 13th century, but it took the French government until 1910 to recognize platinum as a precious metal and until 1912 to assign it a hallmark: a dog’s head (see Tardy’s Poinçons d’Or et de Platine, which is written in French, but the hallmarks are the same in any language). The British didn’t introduce a special hallmark for platinum until 1975.

Platinum may have been a late-comer in achieving precious-metal status. But once it did, it became the white metal of choice, particularly for setting diamonds. Open, lacy Edwardian jewels owed their look to platinum’s strength and ductility. Because of its new position and heightened demand, the price of platinum soon surpassed that of gold. At the turn of the century, work was already under way to find a less expensive, workable substitute. White gold seemed to be the answer, but finding the right “recipe” took time, effort and motivation. Demand for all white gold jewelry before 1900 was not great because platinum was still less expensive than gold. But World War I hastened the development of white gold because platinum – now at the height of its popularity and demand for jewelry – was needed in the making of explosives and non-corrodible crucibles. In the U.S., it was considered unpatriotic to wear platinum jewelry during the war. But white metal jewelry was fashionable, so the search for a substitute picked up.

Techniques for alloying gold with other metals to produce different colors have been practiced since the 18th century. White gold was produced along with red, yellow and green gold (and sometimes blue), popularly used in combination in the late 18th and early 19th centuries and again in late Victorian and 1940s Retro Modern jewelry. But colored gold (other than yellow) was used primarily as decorative accents. When making an entire piece of white gold, the addition of another metal to achieve the color created problems. Nickel made the gold too brittle; palladium made it too expensive. In 1915, Karl Gustav Richter of Pforzheim, Germany, was granted a U.S. patent for his ternary, or three-part, formulation for white gold. He alloyed a combination of nickel and palladium with gold to make it malleable and affordable.

World War II imposed even greater restrictions on platinum than World War I. As more industrial and scientific uses for the metal were developed, there was a greater need for platinum in the war effort. It could no longer be used in jewelry. Fashion’s return to colored gold jewelry lessened the demand for a white metal substitute, but white gold and palladium were used when needed.

INVENTIONS AND PATENTS

Patented mechanisms and designs can offer useful circa-dating clues, if you know how to interpret them. If the patent date or number is known, you can easily retrieve it or look it up. Otherwise, it takes a bit of searching through a patent depository library’s records.

There is often a span of a number of years between a date of first invention and dates of patenting, perfecting, publishing results, commercialization and common use. Discrepancies in secondary sources abound. For example, one source may cite the date a new process was patented, while another may give the date it was actually invented, which could have been one or more years earlier. Supply of the product to the public may take a few more years after a patent is granted. Some patented inventions never “catch on.” In fact, very few of them ever become big commercial successes.

Patents themselves can present interpretive problems, even when a number or date is found on a piece of jewelry. Patents are good for 17 years (design patents for 14), so the year that the patent number was issued may not be the year a piece marked with that number was made (it could have been made later, but certainly not earlier than the year of issue). In addition, while some patents are completely new and innovative, most are improvements upon previous inventions. It is often difficult to track down the first idea for a patented mechanism, and that first idea may not have been the most commercially viable one anyway. It’s also not likely the one most commonly found. In 1849, for example, Walter Hunt of New York invented and patented the safety pin, which bears little resemblance to the safety pin we use today. The idea of the safety pin led to the development of different types of safety catches for brooches. One, now sometimes referred to as the “trombone catch” (a tube and sliding plunger mechanism seen primarily on European brooches), was invented in 1850 in Birmingham, England, but it took a while to come into widespread use. Several other types of safety mechanisms were introduced at the turn of the century. Many brooches continued to be made with simple hook C-catches, even after the swivel-type safety catch that we know today was introduced by B.A. Ballou & Co., patented May 30, 1911.It was called the “bullet catch.”

To avoid circa-dating errors, remember that earlier types of safety catches were still used on brooches long after 1911. Manufacturers were slow to make the change to the new mechanism. Old C-catches on many earlier brooches were often replaced after the safety catch was introduced, so it’s also important to notice if the safety catch is original to the piece. If it is, and it’s the type still used today, it would indicate post-1911 manufacture.

Earring findings are commonly replaced also, especially when necessary to convert from findings for pierced to unpierced ears, or vice versa. The choice of findings for unpierced ears didn’t become available until the end of the 19th century. Even then this “newfangled” finding must have met with some resistance from the trade and the public. The earliest American patent for an “attachment for holding ear jewels” on unpierced ears was issued June 12, 1894. But the earliest evidence of the mass production and marketing of “pierceless ear drops” found so far is dated 15 years later, as shown in a 1909 Sears catalog. This was the screwback, or as it is called in the trade, the French back, earring finding. The earliest patent yet found for a clip earring for unpierced ears was issued to B.A. Ballou & Co. in 1934.

A mechanism that is relatively easy to circa-date, because nothing quite like it existed before or since, is the dress clip and the accompanying armature that makes a pair of clips into a brooch (often called a double-clip brooch). Cartier received the patent in 1927. Other variations and patents soon followed, and dress clips became the most popular jeweled accessory of the 1930s. The earlier versions have hinged flat backs with little prongs on the underside to grip the clothing. Clips were worn by rich and poor alike. Early 1930s patent numbers are often seen on inexpensive rhinestone dress clips. In the late 1930s, the flat-backed findings were replaced by hinged double pinstems, still used occasionally.

GEMSTONE CUTTING & SETTING TECHNIQUES

Other datable innovative designs and machinery relate to the use of gemstones in jewelry, particularly diamonds. Tiffany & Co. introduced the now-famous Tiffany setting for diamond ring solitaires in 1886. The high-pronged mount elevated the stone to show off its brilliance to best advantage. The first diamonds to be set this way were cushion-shaped Old Mine cuts. These were outnumbered (but not entirely replaced) by the circular Old European cut toward the end of the century, after the power-driven bruting machine was invented and patented in 1891. This machine facilitated the rounding of the girdle of a diamond, making production of circular-cut stones faster and easier. Old Europeans, in turn, were gradually replaced by the modern brilliant (American or Ideal Cut), first described and mathematically configured by Marcel Tolkowsky in his 1919 treatise Diamond Design.

By the beginning of the 20th century, caliber-cut rubies, sapphires, emeralds and other transparent gemstones were being cut to fit specific settings. Up until the early 1900s, most cuts for diamonds were based on a circular shape (the marquise, pear and emerald cuts were in use before the turn of the century). But new designs called for new shapes. The geometric lines of what has come to be known as the Art Deco style were ideally suited for geometrically cut stones: baguette, kite, obus (bullet), triangle, half-moon and trapeze cuts. The House of Cartier was among the first to use these new shapes in the first two decades of this century.

Cartier soon turned its attention to the Orient and the moguls of India for inspiration. In 1923, the company created the first of what would be called its “fruit salad” or “tutti frutti” designs, set with engraved rubies, emeralds and sapphires from India.

Another innovative treatment and setting technique for colored gemstones was the invisible setting, patented by Cartier (which called it serti mystérieux or monture invisible) and Van Cleef & Arpels (which referred to it as serti invisible) in 1933. Cartier says it was the first to register a patent for the technique (the name itself was not patented). But Cartier rarely put the patent into practice, saying its use was “inappropriate” for valuable gemstones. This was because the square- or rectangular-cut stones had to be grooved on the underside to slide them onto the metal track holding them in place. The stones had to be cut to fit a particular design and could never be remounted. Van Cleef & Arpels, on the other hand, must have thought the effort worthwhile; from about 1935 to the present, the company has been noted for creating designs featuring invisibly set stones.

GEMSTONE DISCOVERIES: NATURAL AND SYNTHETIC

The hardest substance known on earth, the diamond, was first described by the Romans in the first century. Stones found in alluvial deposits in India were the principal source until Brazilian diamonds were found in 1726. But it was the discovery of the first diamond in South Africa in 1867 and the second, called the Star of Africa, in 1869, that touched off a “diamond rush” that led to the creation of the most powerful diamond cartel in the world: De Beers. Much has been written about the history of De Beers and the diamond trade. Suffice it to say here that after World War II, De Beers restructured the diamond world. In 1948, the cartel began a marketing campaign that launched its now-famous slogan, “A diamond is forever.” In 1954, De Beers took diamond promotion a step further by inaugurating the Diamonds-International Awards for original designs in diamond-set jewelry.

As De Beers is to diamonds, so the name Mikimoto is to cultured pearls. Kokichi Mikimoto successfully grew the first cultured pearls in 1893. These were button or half pearls grown on the inside of the oyster shell. Spherical pearls weren’t produced until 1905 and patented in 1908. Mikimoto was granted a U.S. patent for them in 1916, but cultured pearls met with resistance from the trade and the public. Natural pearl merchants and jewelers such as Tiffany & Co. presented a united front in staunchly refusing to recognize cultured pearls as “real,” going as far as to sign a pact that they would never sell cultured pearls (of the course, the pact did not last). In the 1920s, pearls were the height of fashion. Oriental (natural) pearls were beyond the means of many a fashionable young lady, who capitulated to wearing less-expensive cultured pearls. But Mikimoto also was up against competition from manufacturers of high-quality imitation pearls such as Técla, Deltah, Richelieu and others, most of which were already in business before round cultured pearls were patented. These companies promoted their product as indistinguishable from Oriental pearls. Some of the strands were finished with diamond and platinum or white gold clasps, making them more convincing – and more expensive, but still much less expensive than natural.

The discovery of a new gemstone has always generated excitement in the jewelry world. In terms of circa-dating, these discoveries are likewise exciting, because they help to circumscribe the period during which a jewelry set with these stones could have been made. But as with patents, there may be a span of a number of years between the dates of first discovery, identification and earliest use in jewelry. According to a recently published study by William Revell Phillips and Anatoly S. Talantsev (Gems & Gemology, Summer 1996), such was the case with demantoid garnets, a variety of garnet first discovered in the Ural Mountains of Russia about 1853. It wasn’t identified as green andradite until 1864 (it was first thought to be chrysolite, a.k.a. peridot) and not named “demantoid” (having “diamond-like” luster) until 1878. (A yellow to yellow-green andradite from Piedmont, Italy, called “topazolite,” has been known since the early 19th century.) Once named, the stones gained favor among Russian jewelers. They also were exported to Europe. The Russian Revolution of 1917 curtailed the mining of demantoids (until recently), and jewels set with them were no longer made after about 1920. The period of the demantoid’s greatest availability coincided with the late Victorian and Edwardian taste for green stones. Demantoids were particularly well-suited for setting into animal novelty pins, such as lizards and frogs, which were extremely popular at the time. The newest garnet discovery is another green stone, tsavorite, discovered in Kenya and introduced to the trade in 1974.

Gem expert George F. Kunz, who joined Tiffany & Co. in 1879, was recognized for his talents in gemstone discovery and selection with the naming of a new variety of spodumene, kunzite, first described by him in 1902. The pink stone was well-suited to pale Edwardian-era fashion.

Kunz also was instrumental in calling the world’s attention to gemstones found on American soil. He assembled collections of American stones for Tiffany that were exhibited at the Paris Exposition Universelle in 1889 and 1900. Among the stones that caught Kunz’s eye was the Montana sapphire, first found in the Missouri River in 1865. According to Gordon T. Austin in his article “Montana Gem Production On the Rise” (Colored Stone, March/April 1990), “This discovery was followed by discoveries in Dry Cottonwood Creek in Deer Lodge County in 1889, in Rock Creek in Granite County in 1892 and in Yogo Gulch in Granite County in 1895.” Yogo Gulch, the source of the highest quality blue Montana sapphires, was the first to be developed commercially. Commercial mining on a large scale began in Rock Creek in 1898. It was these “fancy-colored” (colors other than blue) Rock Creek sapphires that Kunz commented upon in 1902, reporting on the display of a Tiffany & Co. corsage ornament at the 1900 Paris Exposition (Steve Voynick, “Rock Creek Sapphires,” Rock & Gem, December 1987). But it was the “cornflower blue” sapphires of Yogo Gulch that played a starring role in the stunning life-size iris corsage ornament designed by Paulding Farnham for Tiffany, which also was displayed in Paris in 1900. It is now at the Walters Gallery in Baltimore Md.

Discoveries of new gemstone sources usually lead to new enthusiasm for even a well-known gemstone, and greater availability allows jewelers to use it more often. Nineteenth century discoveries of opals in several regions of Australia (in Queensland in 1849 and 1872 and in New South Wales in 1889) would logically have led to widespread use of the stone in jewelry, had it not been for Victorian superstitions. As late as 1887, opals were referred to as “misfortune’s stone.” The idea the stone brought bad luck stemmed from Anne of Geierstein, a novel that Sir Walter Scott published in 1829. By the end of the century, however, the public largely had overcome these fears and opals became fashionable.

Just as alchemists had long searched for a magic formula to transform base metals into gold, the desire to imitate nature prompted numerous laboratory experiments in creating synthetics. Dr. Edmond Frémy successfully developed flux-grown rubies in 1877. But these were small stones grown on an experimental basis in small quantities. It wasn’t until 1902 that crystals large enough to be used commercially in jewelry were produced. Auguste Victor Louis Verneuil, a professor of applied chemistry, accomplished it with his flame-fusion process. So-called “Geneva” rubies, which Kurt Nassau (Gems Made by Man) says were produced by a double-torch flame-fusion process, appeared in 1885. These were on the market about 20 years, until the superior Verneuil synthetic rendered them obsolete. Considering the time Geneva rubies were available, it’s curious that extant examples of late 19th century jewelry set with them are difficult, if not impossible, to find. Synthetic blue sapphire was the next challenge for Verneuil. He began to work on it in 1909 and received a U.S. patent in 1911. Synthetic spinel was produced accidentally by flame fusion in 1908, but it wasn’t until the mid-1920s that it was produced intentionally.

An entirely different process called flux fusion was developed for synthetic emeralds. They were first produced in Germany around 1934, but Carroll Chatham was the first to successfully produce and market synthetic emeralds, beginning in 1939. The term “Chatham Created Emerald” has been used for this product since 1963.

After World War II, other new synthetics appeared. Linde Air Products Co. came up with synthetic star rubies and sapphires in 1947. (Linde later became a division of Union Carbide and Carbon Corp.) General Electric successfully synthesized diamonds in 1954, but gem-quality crystals weren’t produced until 1970.

OTHER SYNTHETIC JEWELRY MATERIAL

Anyone who deals in antique and period jewelry is apt to come across pieces made from other synthetic substances with which they may not be familiar. These materials were not initially invented for the purpose of jewelry-making, and while not intrinsically valuable, the jewelry does generate collector interest. Vulcanite, or hard rubber, was patented in 1851, developed from Charles Goodyear’s invention of the vulcanization process in 1839 (patented in 1844). It was ideally suited for use as a jet substitute in mourning jewelry. Vulcanite is often misidentified as gutta percha, which is an entirely natural rubber-like substance (vulcanite has easily detectable sulfur added). Gutta percha was used for utilitarian objects, and perhaps jewelry, but no known examples survive.

Celluloid, the first successful semi-synthetic plastic, was invented and patented by John Wesley Hyatt in 1869. Celluloid jewelry was first made in 1875, as an imitation of jewelry made from natural materials such as ivory, coral, horn and tortoiseshell. In the 1920s, celluloid novelty jewelry in decidedly unnatural colors made its appearance.

The first entirely synthesized plastic was trade-named Bakelite, invented in 1908 and patented in 1909 by Leo H. Baekeland. Generically, it is known as thermosetting phenol formaldehyde. It wasn’t until the 1930s, when the Great Depression created a market for it, that this plastic was used for jewelry (under several trade names). Today, it is highly collectible.

As columnist (and world record-holder for highest IQ) Marilyn vos Savant wrote in a recent column in Parade magazine, “When we take anything out of context … we lose our opportunity to see the whole truth.” Many other factors should be taken into consideration when we analyze old jewelry to determine its age. We must note the more subtle but pervasive influences exerted by historical events, fashion trends, famous people, artistic movements and mass media. These yield important clues to placing a piece in its proper context. Armed with the key dates given above, we can continue our detective work with greater confidence.

I would like to thank Elise Misiorowski, research librarian at the Gemological Institute of America; Sherry Shatz, my research assistant; Ron Spain and Ernie Wilbur of B.A. Ballou & Co.; and Janet Zapata, a decorative arts historian, for their help in preparing this article.

Christie Romero is a jewelry historian, lecturer and consultant. She is the author of Warman’s Jewelry (Chilton, 1995).

BIBLIOGRAPHY

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