Gem of the Month

Each month this section will feature either a topic of interest to gem lovers or one special gemstone with background on the material and its value.

Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment

 

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April, 2003

Amber

Amber, or fossilized pine tree resin, has one of the longest histories of use as a gem. People have long appreciated it's golden colors and many forms, and have always marveled at its ability to develop a static electric charge when rubbed. It's one of the few gemstones of organic, rather than mineral, origin (along with pearls, shell, jet, ivory, and coral) and is today, at an extreme height of popularity.

We're all familiar with resin, the sticky exudate of evergreen trees, which in modern times is mostly a nuisance on our driveways, but has some practical purposes as in improving the grip of athletes and imparting a lovely smell to some household products. Such resins from ancient forests have been compacted and heated by geological processes into gemstones which can range from yellow through orange to brown and even show red, blue, green and black colors. Take a look at a "weeping" pine tree today and you'll see lots of junk inside the resin ball -- insects, plant parts and air bubbles. Such inclusions, trapped in the fossilizing material, alter the color, clarity and transparency of the resulting ambers. Translucent to opaque ambers have air bubbles in them which refract and reflect the light.

The most sought after type of amber in today's market is from the Baltic region, where it can be found as rounded nodules floating in the seas of Eastern Europe, washed up on the shores or which can be mined from underground deposits. In addition to that from Baltic areas, much (somewhat younger geologically) is mined in the Dominican Republic, South America, the US and Africa. There is a notable reddish variety from Burma which is harder and takes a finer polish than Baltic amber, known as "Burmite".

Two avid groups of amber lovers compete over the best pieces -- there are those who value this gem most because of the animal and plant remnants trapped inside ( a la "Jurassic Park"), and those who see it in terms of personal adornment. Much of the amber in commerce today (especially in jewelry) has been enhanced in one way or another. The most common treatments include heating in oil for clarification and heating without oil to darken the color. Also seen frequently are man-made inclusions called "sun spangles". These are stress fractures, deliberately created by heating and then rapidly quenching in cool oil -- the flattened discs, which some find attractive, look something like nasturium flowers.

Beyond enhancement, amber is one of the gems most likely to be simulated. Glass, plastic & synthetic resin imitations and "reconstituted" amber or "Amberoid" can all be readily found especially in inexpensive mass marketed jewelry. Amberoid is made by taking small bits of natural amber and heating and pressing them together into larger pieces. Yellow or orange amber may be dyed to imitate the rarer color forms such as red, green and blue. Geologically young resins such as copal and kauri gum are also sometimes seen as amber simulants. Fossiliferous amber, likewise has been counterfeited -- and the buyer of such is best advised to acquire his/her specimens from a reputable source. (ACS carries only, natural ambers and those which have received no more than simple heat treatments).

There are a couple of tests that can be done in the home to detect plastic imitations. The application of a hot point (the blade of a heated knife or ice pick, for example) to an inconspicuous part of the test stone, will yield either a pleasant piney smell if it is amber, or an acrid buring plastic odor if it is plastic. Likewise, a saturated salt water solution (1/2 cup room temperature water with as much table salt as will dissolve) can separate most plastics, which sink, from most natural ambers, which float.

Amber, at hardness 2 - 2.5 is an extremely delicate gem which must be protected from scratches, knocks, exposure to chemicals (like nail polish remover and rubbing alcohol) and heat. Millions of them are on the market, but amber rings and bracelets, if worn daily, are almost certain to degrade rapidly. Pendants, brooches and earrings can be enjoyed safely, however. To clean amber jewelry or specimens, luke warm water, mild soap and your fingers are the best tools -- be certain to avoid ultrasonic and steam cleaners.

Amber is cut into cabochons, made into beads, used for carvings, and occasionally even faceted.


Value Considerations

Most amber gemstones and jewelry pieces are modestly priced. The highest prices go to large, clean, natural pieces, the rare colors (red, blue, green) and those with the most distinctive and rarest fossils inside.


Gemological Properties:

Makeup: fossilized tree resins (mostly terpenes with succinic acid)

Crystal System: Amorphous

Hardness: 2-2.5

RI: 1.54 - 1.55

Density: 1.08

Polish Luster: resinous to oily

Fluorescence: varies with color and origin

Fracture: conchoidal

Stones Currently Available:

{Search our Catalog}

Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment