Published on JTV.com: August 2012
Cara Williams of Stone Group Labs introduces Bear Williams and Maggie Campbell Pedersen's article on the differences between Amber and Copal, originally printed in Gem & Jewellery News.
This article is not intended to cover all aspects of defining amber and copal, but to bring the reader up to date on current terminology and treatments in order to better understand the following article, “Copal vs. Amber”.
Many of us think we know what amber is, but do we truly? Jurassic Park, the movie, brought it to our attention - brought it to life, in fact. But it can be difficult to separate fact from fiction. Amber and Copal belong to a category of gemstones known as the organic gems. Organic gems are those that did not form by geological forces, but rather by those of living organisms. The best known organic gem is pearl, but coral, horn, tortoise shell, ivory and many others fall into this category. Amber and copal are sometimes called “natural resins”. This is because they form from the resins secreted by plants and trees. Pine sap is a commonly known plant resin, but pine trees are not the source of either amber or copal. Baltic ambers originated from a plant that was a distant and ancient relative of the modern pine tree.
Natural resins are commonly imitated for a variety of reasons. Plastics, Epoxy, Lucite, lacquers, and various petroleum products can be classified as artificial resins. Chemically there are many similarities in addition to their appearance. It is easy to imitate the look of natural resins, but there are means to separate them from the real thing. Natural resins will float in saturated salt water, while plastics and other imitators will sink.
To understand natural resins, it is best to see them as part of a continuous spectrum. Copal is merely a term for young, “unripened” amber. Finding the dividing line is not so simple; different sources define them in different ways. A long-established standard has been that ambers are at least ten million years old and any resins less than this are considered to be copal. Modern treatments and the way resins have been labeled are challenging the old standards.
Many of the standards are based on the Baltic amber market, the oldest and most prolific source since early history. Baltic ambers are those that wash up on the shores of the Baltic Sea in northern Europe. They are also found by mining in several areas of Scandinavia and northeastern Europe. Poland, Russia, and Lithuania are well known for their amber markets, and ambers feature prominently in the jewelry designs of this region. Baltic ambers can vary widely in their appearance, but they are all at least 10 million years old (most are 30-40 million years old) and all were produced by now-extinct trees known as pinus succinifera. These trees were like nothing we know today and produced a prolific quantity of resin. So it makes sense that many living and organic things would be trapped and preserved within these copious resins. Resins will burn (frankincense is a resin ) and will also disintegrate back into the soils. Those that survive to our era, the material we know as amber, were trapped under the earth or buried under oceans and allowed to slowly age and harden over millennia to a more durable state. It is this ripening process that distinguishes amber from copal. Amber is slightly harder, more stable, and more durable than copal. The rate at which this ripening process occurs depends on the specific environment. And like many natural processes, it can be imitated in controlled laboratory environments.
While Baltic amber is the best known amber, plants that produced amber-forming resins also grew in other regions of the world. Mexico, the Dominican Republic, Myanmar (Burma), Indonesia, and other places regularly produce amber. It is not always possible to determine the origin of ambers, but in most cases it is possible to tell if the material is of the Baltic type, coming from the pinus succinifera trees. This is done by infrared testing equipment (FTIR).
Copal is found in many places and is still being produced today. Most frankincense is copal. It is a resin that has dried and solidified, but burns with a an aromatic scent. If you have seen it, it can be crumbly looking. This is not gem-grade copal, but rather copal that has begun a natural process of drying and degrading. When left open to a normal atmosphere, certain elements within the copal will evaporate. These are known as “volatile compounds”. In an uncontrolled environment, the departure of these volatile compounds can lead to the disintegration of copal – it turns to dust. It is common to see a network of fine cracks on the surface of copals, and this “crazing” often signals the initial stages of this process. But in a controlled environment – either buried in the earth, under the sea, or in a lab environment – the resin will remain cohesive and become stable. The primary sources for copal are Colombia and the island of Madagascar. The New Zealand Kauri Gum is also copal, named for the Kauri trees that still produce it. They are revered, endangered and protected, so we do not see much of this in the market. Copals can be very young, sometimes nearly new to only a few hundred years old. So they can benefit greatly from an artificial aging process. Some copals can be millions of years old and well along their way to becoming amber.
A number of treatments have been done to amber for centuries. Amber is not crystalline, like some gems, and it has the ability to soften or melt and reform. This property is called thermoplasticity. While much amber remains natural - aside from shaping and polishing - lower grades are commonly “reworked” to make larger pieces from small, improve clarity, alter the color, or add dyes. But until recently, the final product has remained amber or copal, same as it started; and these processes have always left clues that a carefully trained observer can identify. Like many gemstones, as newer technologies have become available, new treatments have been developed. The following article addresses these treatments and how they might be identified.
Note: The following article originally appeared in a British publication and therefore follows British spelling rules. Colour = color, and gemmology has two “m's”. For further information on this topic, Maggie Campbell Pedersen's book, Gem and Organic Materials of Organic Origin is an excellent reference on resins and other organic gem materials.Read Part 1 Read Part 2