How to Understand Gems

The term "gemstone" normally refers to minerals that have been cut and polished. Not every mineral can become a gemstone, though. Minerals with a particular visible beauty that exhibit both a natural stability and hardness make excellent candidates. These minerals also need to be in masses or crystal forms that jewelers can cut and work. Minerals that possess all these attributes are understandably rare and it for this reason that gemstones are so valuable. Although in excess of 4,000 minerals have been described, as few as 20 are traditionally sources of gemstones.

• 1

  View the gem through either a 10 x loupe or under a microscope, depending on the size of the stone.

• 2

  Look at the general shape of the gemstone. This will assist you to place the stone in a class of gemstones. Minerals are classified in 10 different classes, based on crystal chemical composition. Minerals within these classes that possess a well-defined physical structure and chemical composition are given species status.

• 3

  Refer to the gemstone reference book. The species of gemstones include beryl, corundum, opal, spodumene, zoisite and zircon. Using color and shape at this point, you can identify down to species level in many cases.

• 4

  Look for visible inclusions, which are internal fractures or traces of various growth stages of the gem. These inclusions are made up of minute crystals that became part of the gem as it was forming. These inclusions are a means of identification and will indicate if the gem is natural or synthetic.

• 5

  Pay particular attention to the inclusions that you find. The green color of aventurine quartz, is derived from flakes of fuchsite that have been caught within the aventurine stone. The six- or 12-pointed star shape in a star sapphire derives from inclusions of another crystal, known as rutile.

• 6

  Refer to your commercial classification list. These lists organize gemstones according to how popular or well known the stone is. Emerald, ruby and sapphire will be included as the best known gemstones, while iolite and andalusite will be classed as lesser known gemstones.