Crystals
Crystals are easy to distinguish because they are always angular. Finding a crystal inside a stone usually indicates you are seeing a natural gem. The exceptions are few and easy to learn.
Phenakite crystals show up in flux grown emerald. They are always in low relief and are usually associated with flux veils, which is a primary clue to their identification.
Hexagonal platelets are another item that requires attention. Both hematite and platinum crystallize this way. Hematite in a gem indicates that it is natural in origin; platinum means it is a synthetic.
Occasionally bubbles will take a regular shape, so you need to compare all the information at hand, rather than relying solely on these inclusions to indicate a natural origin. Fortunately, inclusions usually come in groups.
Of special interest are rutile inclusions. They are long, straight and usually flat. They are usually gold colored but sometimes they are red. These are only found in quartz and tourmaline. When found, you only have to distinguish between these two species.
Long thin, black needles are often confused with rutile. These are actually tourmaline needles and are common in quartz. Sometime…
IGS Newsletter