INCLUSIONS IN SYNTHETIC GEMSTONES
A perfectly clear stone, without flaws or inclusions (internal features of gemstones, such as solids, liquids or gases, that have become enclosed within the gemstone during or after formation) is usually a warning sign to a gemologist that the stone may be synthetic. However some synthetic gems may be identified by the type of inclusions, formed as a result of the method of manufacture. Flame-fusion gem-stones may include specks of the powdered ingredients that have failed to melt sufficiently, and have curved growth-lines, rather than the straight lines that develop in natural specimens.
Synthetic-flux emeralds may have inclusions of the minerals phenakite or platinum, twisted veils and feathers (characteristic patterns of inclusions), and two-phase inclusions (a liquid and a solid). Synthetic hydrothermal emeralds usually have only a few inclusions, possibly of phenakite and occasionally very fine two-phase inclusions.
natural inclusions
Natural inclusions may be specific to one gem or even to a particular country or mine. Emeralds, for example, tend to be so heavily included that the view down a microscope (X40 magnification) is sometimes referred to as jardin (French, 'garden'). Natural emeralds may have inclusions of the minerals mica, tremolite, actinolite, pyrite, or calcite. Colombian emeralds may contain characteristic three-phase inclusions (solid, liquid, and gas), with a cubic salt crystal and a gas bubble within a fluid-filled cavity. Other gemstones with characteristic inclusions include peridot, which has inclusions that resemble 'lily pads' (liquid droplets around a crystal of chromite) and the 'treacly' appearance of hessonite garnet.
