Semi-Precious Stones
The "Precious Four" Gems
The term semi-precious is used to refer to the entire world of colored gemstones, not including the four so-called precious gems, diamond, ruby, sapphire and emerald. The terms precious and semi-precious are actually no longer used in the gem trade, and the American Gem Trade Association (AGTA) officially requires that "Members should avoid the use of the term 'semi-precious' in describing gemstones". This rejection of the term semi-precious is a way of recognizing the incredible diversity and rarity of many colored gemstones. One of the major changes in today's gem market is a growing consumer awareness of the vast range of colored stones. These days customers ask us about sphene and iolite and other previously obscure gem varieties just as often as they ask us about sapphire or emerald. At the very least we need a classification for what we might call premium colored gems. These are gems that have excellent gemstone characteristics - hardness, durability, brilliance, clarity and color. In most cases they are also quite rare. These could be considered to be the new precious gems. This group would include not only ruby, sapphire and emerald, but also spinel, tanzanite, tsavorite garnet, demantoid garnet, alexandrite and the finer tourmaline.
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Another useful categorization is grouping gems that have good gemstone characteristics, but are widely available and very affordable. These include members of the quartz group - 
- Впервые опубликовано: March-18-2008
- Последняя редакция: November-08-2017
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