Is it real?

The definition of synthetic is material created in a laboratory using basically the same ingredients found in the natural products (Matlins and Bonanno, 1998, p. 123). Some synthetics have no natural counterpart. Synthetic gems have identical physical, chemical, and optical properties as the natural gem material, for the most part. An exception to this, is in the coloring chemical for some synthetics, which can be different from the natural coloring agent. Even though synthetics may replicate the natural gem, they must be identified and prefaced with synthetic, created, cultured or some origin indicator.

An imitation is an artificial likeness or copy, which could mean a synthetic material or natural gemstone. Imitations are not exclusively synthetics and not all synthetics are meant to imitate! Some synthetics are marketed as a gem in their own right, such as CZ or cubic zirconia. Although it should be prefaced, synthetic CZ, it is often advertised without the synthetic preface; it does have a counterpart in nature, but it is extremely rare. The term imitation is usually applied to glass and plastic although it can refer to natural minerals too. The golden-colored quartz, citrine, has been used to imitate topaz in birthstone rings for so long, that many people have a difficult time accepting natural colors of topaz. Topaz can be colorless, pink, pale brown, sherry-colored (reddish-orange) and less commonly, yellow.

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Created Imitations

A modern example of faience with a scarab motif.
Specimen provided by Barb Robins. Photo date 3/04, © by S.W. Aber.

Another example of an imitation is hematine, which is both a synthetic and imitation. Hematine is a created simulator of stainless steel with chromium and nickel sulfides. It is made to imitate hematite. The two can be distinguished by a streak and magnetism. Hematite has a reddish-brown streak, whereas hematine has a brown-black streak (this test is destructive though!). Hematine is strongly magnetic, whereas hematite is typically not magnetic.

Photo date 3/02, © by S.W. Aber.	Photo date 2/02, © by Berg and Dougan.
A bracelet with hematine and aventurine quartz beads is shown on the left. Note magnet attached to the specimen! A hematite ring and earrings are shown on the right.

Glass is amorphous or a created, inorganic substance which is mixed in a molten form and cooled to a rigid form without crystallizing. There are two main types of glass: crown and flint. Crown glass is made with silica, soda, and lime. It is used for bottles, window and optical glass, and costume jewelry. Flint glass is composed of silica and soda, and lead oxide or other metal oxides replacing the lime. This type of glass has been called strass (or stross) after the Austrian who is credited with its discovery, Joseph Strasser. Flint glass was used to substitute for diamond and because of this, was prohibited in the 18th century by Empress Maria Theresa (Schumann, 1997, p. 242). Glass imitations have been referred to as paste, which is from the Italian pasta meaning dough, "because the ingredients are mixed wet to assure uniformity of the batch" (Hurlbut and Kammerling, 1991, p. 150).

Stones cut from flint glass resembles the gems they are meant to imitate because lead gives a greater dispersion and higher refractive index. Coloring glass is accomplished using a metallic oxide: a purple color is derived from manganese; blue from cobalt; red from selenium or gold; yellow and green from iron; red, green, blue from copper; green from chromium; yellow-green from uranium; and amber glass from a combination of manganese and iron, and no amber at all! "The final color of the glass is also affected by such factors as the type of glass used, the oxidizing or reducing conditions used during manufacturing, and annealing after manufacture. Colorless glasses are made by adding decolorizing agents called glassmaker's soaps; these reduce the greenish tint that otherwise ensues from iron impurities." (Hurlbut and Kammerling, 1991, p. 151) Many cheap glass imitations are foiled, that is the pavilion facets covered with a thin metallic film that acts as a mirror to enhance brilliance and sparkle. Colorless glass can be given a face-up color, or color looking down at the crown, by covering the pavilion with a colored film. A translucent look can be achieved by adding tin oxide.

Some of the more common glass imitations are discussed below. Glass can be beautiful and an inexpensive alternative to natural gemstones.

Glass Opal
The Slocum stone, developed by John Slocum, is an interesting imitation of opal. It is glass that has various body colors of white, black, near colorless, or orange (fire opal). The flashes of color are produced with metal foils that looks like colored cellophane in transmitted light and resembles parts of a puzzle (Hurlbut and Kammerling, 1991, p. 153). Opal synthesis succeeded in the United States in 1970 (Schumann, 1997, p. 152). Enhancements can be made by coloring black or matrix opal or impregnating opal with artificial resin (Schumann, 1997, p. 152).

Goldstone
Goldstone is colorless glass with flecks of precipitated copper crystals, which result in the glittery aventurescence phenomenon. Deep blue and green goldstone can also be found.


Cat's Eye Glass

Photo date 3/02, © by S.W. Aber.

Fire Eye is made of ..."parallel, tubular gas bubbles produced by aeration, the same process used to carbonate soft drinks" (Hurlbut and Kammerling, 1991, p. 153). Other glass cat's eye material is produced by fused optical glass fibers, some with distinct hexagonal cross sections for the fibers giving it an overall honeycomb effect. "Still another chatoyant glass, Victoria Stone, is partially devitrified and exhibits a silky texture in the recrystallized areas" (Hurlbut and Kammerling, 1991, p. 153). Blue fiber optic rough and cabochon cut is pictured to the left.

Color Change Glass Alexandrium is a trade name for glass that changes from pink to violet in incandescent to fluorescent lighting; Tourma-like is a trade name for glass that changes from pinkish orange to yellowish green in incandescent to fluorescent lighting (Hurlbut and Kammerling, 1991, p. 153). Zandrite is another trade name for color changing glass (http://www.yourgemologist.com/zandrite.html).

Glass Pearls Some 300 years ago, hollow glass beads were lined with essence d'orient, an iridescent material from fish scales, and filled with wax (Hurlbut and Kammerling, 1991, p. 153). Translucent white glass beads with coatings of essence d' orient serve as imitations today. Glass and imitation plastic pearls will feel smooth when rubbed lightly against front teeth, while cultured and natural pearls feel gritty (Hurlbut and Kammerling, 1991, p. 153).

"Until 1945, Gablonz and Turnau in Czechoslovakia were important centers for the glass-jewelry industry. Then this tradition was taken over by Neugablonz in Allgau, Bavaria." (Schumann, 1997, p. 242). Porcelain, enamel, resins, and plastics also serve as gem imitators. Plastics are formed by heating and/or molding, and called celluloid (cellulose plastic), bakelite (phenol-formaldehyde), plexiglass or lucite (methyl methacrylate resins), polystyrene and polyvinyl resins. The plastic is constructed of long, chainlike molecules called polymers and have a very low hardness. They are sometimes faceted but usually cut en cabochon to imitate gems such as amber, turquoise, jade, and pearl to name a few.

Plastic pearls with paint coming off. Photo date 3/04, © by S.W. Aber.

Plastic brooch meant to imitate citrine quartz and jade. Photo date 3/04, © by S.W. Aber.

Plastic cameo meant to imitate shell or sardonyx. Photo date 3/04, © by S.W. Aber.

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Synthetic Gemstones

A German chemist, I. Czochralski, developed another synthesis method in 1918, where the boule is drawn out of the smelting after a crystal nucleus has been created. While rotating the boule is continually drawn upward and grows on the underside also. In recent years crystals have been flux-grown, a created method that more closely resembles natural crystal growth. These laboratory-grown synthetics are more expensive to produce than other methods, but can still make a good alternative for consumers who are unable to afford natural gemstones (Matlins and Bonanno, 1998, p. 124).

Some synthetic imitations of diamond include: synthetic rutile (also known as titania or diamonite, created in 1948); fabulite (occasionally called diagem, created in 1953), strontium titanate (SrTiO₃); YAG (also called diamonaire, created in 1969), yttrium aluminum garnet (Y₃Al₄O₁₂); GGG or galliant, a gadolinium gallium garnet, (Gd₃Ga₅)O₁₂; djevalite, a calcium zirconium oxide (ZrO₂/CaO), linobate, a lithium niobate (LiNbO₃), cubic zirconia (also known as fianite, phianite, or KSZ), and yttrium zirconium oxide (ZrO2/Y2O3) (Schumann, 1997, p. 242-3, 246). Most recently moissanite, silicon carbide, has become a popular diamond imitation (developed in colorless gem quality in 1996, produced by Cree Research Inc., distributed by C3 Inc.) (Nassau, McClure, Elen, and Shigley, 1997, p. 261).

Visit some created gemstone webpages... Chatham Created Gems, www.chatham.com/, Tairus Created Gems, www.tairus.com/, and Ramaura Cultured Ruby, www.ramaura.com. (Tairus must be viewed with Internet Explorer for best results.)

Chatham has information about

Tairus has interesting pages including

While the founders of Ramaura have retired, the company still has online information on

• the ruby recipe at www.ramaura.com/recipe.htm
• an image essay on the procedure for growing ruby, www.ramaura.com/making.htm

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Composites or Assembled Stones

Garnet and glass doublet was once a commonly encountered composite stone, especially before synthetics became routine. Glass is fused to a slice of garnet, usually almandine. Garnet is found in the crown for color and durability. Garnet and glass doublets have been constructed to imitate garnet or diamond. Other doublet imitations of diamond include: foil-backed glass, rhinestones or foil-backed rock crystal quartz, and colorless spinel or corundum with a pavilion of strontium titanate. Corundum doublets, meant to imitate ruby and sapphire, can be a natural corundum crown glued to a synthetic corundum. Emerald triplets, meant to imitate emerald, consist of natural colorless beryl, colorless quartz, or colorless synthetic spinel, joined with a green cement.

Opal and ammolite (fossilized shell of ammonites in form of aragonite) are found in thin veins or structures. When used as jewelry, these two gems are commonly found as doublet or triplets to increase its durability and make to most of the rough material recovered.

Black opal triplet. Photo date 3/04, © by S.W. Aber.

It is common to cement a thin slice of opal or ammolite to a backing. The backing could be a piece of common opal, black glass, or dyed black chalcedony. The triplet would be assembled the same way, except with a convex cap of clear quartz, glass, synthetic spinel, or synthetic sapphire is cemented to the top of the opal or ammolite section. Visit Ways to Cut Opal, http://uniqueopal.com/cut.html, for more information on opal composites. Visit Korite International, http://www.korite.com/ammolite.html.

Diamond and diamond doublets are called "piggy-back" diamonds. Another diamond doublet involves a diamond crown and colorless quartz, synthetic sapphire, synthetic spinel, or glass on the pavilion. Jadeite triplets are constructed of a colorless jadeite hollow cabochon glued to a flat base, with the hollow dome filled with a green jellylike substance (Hurlbut and Kammerling, 1991, p. 162). Imitation cat's eye could be assembled from a hollow cabochon of synthetic corundum, filled with fibrous ulexite (often called TV stone!), glued to a base of a shallow cabochon of synthetic corundum. The opal imitation could be a cabochon of colorless glass or plastic glued to a base of mother-of-pearl shell.

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The material for this section came primarily from:

• Hurlbut, C. S., & Kammerling, R. C. (1991). Gemology. NY: John Wiley & Sons, Inc.
• Matlins, A. G., and Bonanno. A. C. (1997). Gem identification made easy. Woodstock, VT: GemStone Press.
• Matlins, A. L., and Bonanno, A. C. (1998). Jewelry and gems the buying guide. Woodstock, VT: GemStone Press.
• Nassau, K., McClure, S. F., Elen, S., and Shigley, J. E. (Winter, 1997). Synthetic moissanite: A new diamond substitute. Gems and Gemology, vol. XXXIII, p. 260-275.
• Schumann, W. (1997). Gemstones of the world. NY: Sterling Publishing Co.

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This page originates from the Earth Science department for the use and benefit of students enrolled at Emporia State University. For more information contact the course instructor, S. W. Aber, e-mail: saber@emporia.edu Thanks for visiting! Webpage created: November 15, 2000; last update: March 2, 2008.