One in every one thousand pieces of Baltic amber contains an inclusion, either organic or mineral; for amber originating from the Dominican Republic the figure is ten times higher. Eighty percent of the world's amber is Baltic amber though, and so most amber inclusions are actually found in pieces of Baltic amber.


 Amber containing inclusions is much sought-after and is therefore significantly more expensive, especially the larger and showier pieces containing examples of complete preserved insects which are used in the manufacture of some amber pendants, necklaces or rings; traditional craftsmen have been doing this for centuries with Baltic amber. Of course, amber containing inclusions is also purchased by fossil, mineral and gemstone collectors merely for their own pleasure.


Because of its age, examples of modern species of insects are not naturally found as inclusions in Baltic amber; it was formed over fifty million years ago and no species from that period of geological history remain unaltered into the modern age. There are however, reports of holes being drilled into amber, insects being inserted, and then the hole plugged with resin of a colour matching that of the amber. Modern insect species are found embedded in South American copal, a similar material to amber, which is softer though because it was formed much more recently.


Sulphur and pyrite, also known as 'fool's gold' are examples of inorganic inclusions: so called 'black inclusions' can consist of decayed plant material, carbonated wood, pine cones and needles, or bark – all indications of the environment of dense pine forests which existed at the time when Baltic amber was formed.


Entombed lizards, or other more exotic specimens, always attract attention, but over half of the creatures trapped in Baltic amber are flies.


Seeds, flowers, leaf imprints, mushrooms, the bones of small mammals, feathers or fur have also been noted in pieces of amber; and the disc-shaped fissures or sun spangles, particularly popular with the makers of amber jewellery are believed to be examples of trapped water droplets or air bubbles.


When the sun spangles appear to have darker edges this means that the amber has been 'clarified'; a process whereby the amber is immersed in rapeseed oil and slowly heated – these naturally occurring air bubbles alter the way in which the light is reflected and therefore gives the amber a cloudier, and less attractive, appearance. The technique of heating fills the spaces with oil, which better reflects and refracts the sunlight – giving the amber its wonderful and magical jewel-like attractiveness. In addition, the air trapped within these air bubbles can be used to study the Earth's atmosphere as it was at the time when the amber was formed; in the case of Baltic amber, over fifty million years ago.


So, if your treasured item of Baltic amber jewellery contains an inclusion, it's not just a fossil imprint from all those millions of years ago; but it's the actual atmosphere from the Cenozoic Era, or some water from the period, or decaying plant matter...or a genuine pre-historic insect. That's quite a tale to tell the grandchildren.