CHERRY AMBER, AND OTHER RED AMBERS
Amber, the fossilised tree resin that is many millions of years old, can be found in various countries world wide. The best known is Baltic amber. This was formed about 35,000,000 years ago in the forests that covered an area that is today Scandinavia, the Baltic countries and the Baltic Sea. In some of the countries that surround the Baltic Sea amber is industrially mined and exported in large quantities -- especially from Lithuania, Russia and Poland. Baltic amber accounts for about 98% of all the amber on the market today.
It is not uncommon today to find beads or other items of jewellery for sale at antique markets, or online auction houses, that are described as ‘red’ or ‘cherry’ amber. What is this material, and is it real amber? The answer is: some is – and some isn’t.
Several ambers can look red when light is passed through them. Some Mexican amber can display a beautiful, deep red colour, and the rather dull brown amber of Borneo can take on a wonderful red hue when viewed this way. Historically, there may have been some transparent red amber in China, but it is believed that most of the red material carved there was imported from Burma (now Myanmar). It was in this country that the real ‘red’ amber was found. Burmite – amber from Myanmar – is now known to be about 100 million years old and as such is the oldest amber used in the decorative arts. For at least 2000 of those years, and probably a lot longer, it has been highly prized as a gem and decorative material. It is found in the Hukawng Valley in Kachin State, in the mountainous northern area of the country. Not surprisingly, burmite is slightly harder than other ambers, and much of the material is cracked. Calcite is sometimes found in the cracks. There is a great variety of insects and some flora in burmite, though they are not always as well preserved as those in other ambers. The colours vary from an opaque brown variety (called ‘root amber’, though golden shades to brown. A lot of it has a red tinge depending on the angle of light, but a small amount – probably less that 2% -- is a clear red.
Piece of burmite rough, slightly larger than actual size.
Fresh, natural Baltic amber never occurs in a red colour, nor does it appear red by transmitted light, though it can acquire a reddish patina with great age. The surface of the material oxidises and darkens, making the amber look anything from orange through rust red to brown, and usually opaque. Thus examples of Stone Age amber carvings that can be viewed in museums are normally dark rust colour. If they were to be re-polished, it would be seen that this colour is only on the surface, and that underneath the amber is paler.
Heat-treated Baltic amber beads. The final polish removes
a little of the darkened surface from the facet edges.
This phenomenon has been copied by treating Baltic amber. Most of the new Baltic amber on the market today has been processed in some way, and much of the treatment is perfectly acceptable. Altering the colour and clarity of amber is not a new idea. The Romans were treating Baltic amber to enhance it 2000 years ago. They could clarify opaque amber and darken its surface by boiling it in pig fat or rapeseed oil. Today we use more modern methods which are often closely guarded secrets. A basic process would consist of heating the cut and polished pieces of amber in an autoclave, which results in the material clarifying and the surface darkening to whatever shade is desired. A dark, reddish brown surface will appear as a red hue, and the material will look very red by transmitted light. The darkened surface is permanent but can be removed by re-polishing. This material is often popularly termed ‘cherry amber’.
Reconstituted and clarified Baltic amber, coated with a red dye. The dye can be partially removed with acetone, and leaves red residue on the string. Inside the beads are totally colourless.
Another more recent method involves reconstituting powdered amber and clarifying it till it is totally colourless. It is then coated in a red dye. Although the body of the material will test positive for Baltic amber in a laboratory, such material has more in common with plastic than with the natural material.
There are other materials on the market that are called red, or cherry amber, which are not amber at all, but are imitations or ‘simulants’. As red amber has always been sought after, it has been imitated in less expensive materials, notably early plastics. Such imitations were very popular in the early to mid twentieth century, when good quality fakes were mass produced in cast phenolic resin. Often called by the gem trade ‘Bakelite’, it is a phenol formaldehyde polymer which is closely related to Bakelite but formed by another process. The material was usually made into beads.
Cast phenolic resin beads (often called Bakelite), left: opaque, and detail of extruded pattern, and right: transparent, and detail of soft facet edges.
The best way to identify red amber is by sight. No natural red amber is opaque, and when a light is shone through an opaque bead it is seen that the colour occurs in streaks, caused by the production method. (The plastic material was extruded in long rods which were later cut, shaped and polished). Although there may be swirls of opaque and transparent material in natural Baltic amber, it is not in almost parallel lines.
Objects that have been moulded will not show stripes of colour, but may show swirls. Like the extruded plastic, they may also contain occasional air bubbles, and although amber can naturally contain air bubbles these tend not to appear singly and render the amber unsuitable for carving.
Total absence of any form of inclusion or blemish inside a row of clear, red beads is also a warning sign, as amber is seldom, if ever, totally free of inclusions. Plastic beads may be moulded instead of carved, so there may be a lack of signs of carving, and soft facet edges. But probably the best indicator with beads is the overall colour. If it is very uniform the beads are unlikely to be amber because, being a natural material, amber does not occur naturally in evenly coloured pieces.
Treated Baltic amber will have been given a final polish which removes a small amount of the darkened surface. This is more noticeable on the facet edges. (See illustrations above.) Careful examination of an item can also show features such as surface blemishes, where the surface colour may have been scratched away, for example by the pin of a brooch, showing clear material beneath. This indicates that the item is heat-treated amber, though there exist today examples of yellow beads made of a mixture of powdered amber and plastic, which have a coating of red dye.
Modern plastic imitating rare red amber from the eighteenth century.
The mouse is far too modern in style.
In the case of carvings the style and the size of the piece are the first indicators. It was extremely rare to find burmite in large pieces, and the ‘red eighteenth century amber carvings’ sold on popular online auction sites are frequently modern in style.
It is also possible to come across items such as small figures or scent bottles that are made of burmite, but not carved from one piece. This was a popular method of ‘faking’ antiques, used in the about the 1960s. Small pieces of burmite were welded together to form a block, which was then carved. Unless closely inspected, the item appears to be made from a single piece and have the typical, slightly reddish glow of burmite when viewed from various angles.
Left to right: scent bottle made from blocks of burmite welded together; detail of the same; plastic imitation of burmite scent bottle.
The same tests can be used for burmite as for any other amber. (See ‘A Background to Amber’) The material has a lower specific gravity (SG) than salt water, so it will float whereas almost all plastics -- including cast phenolic -- will sink. This test can only be of use for unmounted jewellery, as the weight of the metal would weigh down the amber. It is a very good method for carvings, as it is totally non-destructive. (NOTE: care must be taken to wash the item thoroughly in clean water after immersion in salt water, to remove any residue of salt from small fissures as it will dry to a white powder.)
Burmite displays very strong blue fluoresce when viewed under ultra violet light (UV). Even in sunlight the material can fluoresce noticeably. Freshly cut or polished Baltic amber fluoresces with a paler blue colour, which fades to yellow with time. Heat-treated Baltic amber shows only weak fluorescence, and material coated in a synthetic material will show none at all as plastics seldom fluoresce.
Another test is the hot point test, where the red-hot point of a metal object such as a pin is pressed against the object being tested. This is a destructive test and will leave a mark. (NOTE: There is also the risk that the material in question could be of inflammable material such as celluloid.) A safer version of this test is to take a minute scraping of material for burning, from an unobtrusive area, e.g. the drill hole of a bead. The purpose of the test is to evaluate the smell of the material being burned. Ambers generally smell slightly resinous, whereas plastics smell acrid.
The sectility test --- taking a tiny scraping -- is in itself, a test for amber versus plastic, as plastics tend to pare while amber splinters.
The test that is most conclusive, though not infallible, is an FTIR photospectrometry reading, which must be done in a specialised laboratory.
Australian amber, polished, viewed in a mix
of incidental and transmitted light, giving it a
very red appearance.
©2018 Maggie Campbell Pedersen. All rights reserved.