a publication of the International School of Gemology 8 August 2015

Gemstone Marketing: Amber

 

Source: Baltic Sea Region and the Dominican Republic

Chemical: Fossilized tree resin of approximately 100 million years old to be true amber

Formation: Sedimentary deposits of ancient coniferous trees. Amber is the fossilized resin of these tress and is often found to contain small plants and insects from the periods of Jurassic to Cretaceous. Amber should not be confused with copal resin which is also tree resin but is no where near as old as amber, and is therefore not as hardened or long wearing. Some of what is sold as “copal amber” from Colombia and other locations has been found to be less than 250 years old.


Crystal System:
None. Organic

Unusual Properties: Amber with identifiable insects and plants are quite rare and valuable. However, care should be take when buying expensive amber pieces with insects or plants inside. There are numerous verified reports of copal being heated and softened, and then bugs being pushed inside a piece by unscrupulous dealers who then sell them as expensive amber.

Colors: Light yellow, green, dark reddish orange, and many variations of these as well.

Wearability: Will be damaged by jeweler’s torch. Will burn/melt if subjected to heat. Amber has been into many different types of jewelry items for centuries.

Treatments and Imitations: Copal resin and plastic are often used to imitate amber. More on that topic below. At the 2013 JCK Las Vegas show we found Russian dealers who were treating amber with an HPHT treatment to get unusual red, green and yellow colors. This material is quite easy to identify based on specific gravity and inclusion.

Identification: Separating true amber from copal or plastic is fairly easy using specific gravity and fluorescence. An outdated test using a hot point has been published for many years, but the damage to the amber piece is irreparable. As seen below, the use of specific gravity and fluorescence is diagnostic in most instances where separation of suspect material is required.

Specific Gravity: The SG of true amber will vary but in general will be around 1.05. Plastic and most copal resin will have a higher SG in the 1.15 and above range, depending on factors such as included gas bubbles. As a result, all will sink in a bowl of pure water. However, by adding table salt to the water and bringing the specific gravity of the water up just slightly, true amber will float fairly quickly while plastic and copal resin will tend to remain at the bottom for a far longer period of time as the salt is added to the water. A demonstration is below:

 

A group of five (5) suspected amber specimens are placed in a bowl of water. All five specimens quickly sink to the bottom of the bowl where they remain.

 

 

 

 

 

Regular table salt is added, small amounts at a time. The addition of small amounts of table salt increases the specific gravity of the water slightly. By adding the table salt in small increments the water SG can be elevated in small steps.

 

 

 

 

 

As the water becomes more salty, the specific gravity increases and the water becomes slightly cloudy.

 

 

 

 

Shortly after adding a small amount of salt the specimens begin to suspend in the water, neither floating or sinking, but easily suspending up and down in the salt water solution.

 

 

 

 

 

With about one full teaspoon of salt added, three of our suspected specimens float to the top and are quite buoyant in the water. Two of the specimens remain at the bottom and do not suspend or float at all.

 

 

 

We confirm that the two pieces that stayed at the bottom and did not float in the salt water solution are indeed plastic imitations of amber that were added to this parcel to defraud the buyer. By “padding” parcels of natural amber with realistic looking plastic or copal pieces the seller can greatly increase profits and claim lack of knowledge of any problems later on.

 

 

Amber Fluorescence

Another test to help separate copal or plastic and true amber is the use of fluorescence. Below left is an image of copal (left) and true amber (right) in ambient light. In the image below right, taken in short wave UV, you can easily see that the copal is inert while the amber is producing a pale blue color as predicted.

There are other diagnostic tests but virtually all are extremely destructive to the suspected specimen, and are therefore of little use to the professional gemologist. By studying amber inclusions, and testing with UV and specific gravity as shown above, you should have no problem separation true amber from its imitations.

We hope this information is of service to our ISG Global Community. Please send us recommendations and suggestions to help us make this a better and more profitable service for you. Use this link to contact us: Contact the ISG

 

©2015 International School of Gemology. ALL RIGHTS RESERVED. We encourage sharing and caring throughout the industry as long as all copyrights are left intact. Some photographs were taken from various dealer internet sites for demonstration purposes. All photographs are copyright and the property of their respective owners.