What are Different Types of Semi-Precious Stones
The meaning of gem stone is mentioned in the dictionaries as “a precious or semi-precious stone, especially one cut, polished, and used in a piece of Jewellery”. In simple terms it is just a piece of mineral which is cut to a specific shape and then polished to give it shine and then used in jewellery to be worn as ring or pendant or other forms. There are some which are not minerals but since they are used in jewellery they are considered gem stones.
There are two forms of gem stones, the precious gem stones and the semi precious gem stones. The precious stones are primarily diamond, ruby, sapphires and emeralds. All other gemstones are considered semi-precious. The primary reason for considering a gem stone precious is its rarity. If it is rare it is precious and thus costlier.
There are over 100 minerals which come under semi precious gems. Some of the semi precious stones are mentioned hereafter. Aamethyst, rock crystal, carnelian, rose quartz, topaz, aquamarine, agate, tiger’s eye, tourmaline, aventurine, moonstone, jasper, citrine, ametrine, jade, howlite, hematite, malachite, obsidian, turquoise. Lapis lazuli is a semi precious gem which is not a mineral. Opal happens to be mineral deposit close to places where lava flows or once flowed. Pearl are made in the oysters.
There are close to 2,000 known natural minerals and yet only around 100 odd are used as gemstones. Out of these 100 plus primarily 16 are popular. Some of these are beryl, jade, opal, topaz, diamond, garnet, quartz, tourmaline, etc. Some other names of gemstones include alexandrite, aventurine, bloodstone, chrysoprase, coral, jasper, kunzite, moissanite, moonstone, obsidian, pearl, peridot, rose quartz, tanzanite, and tiger eye.
The semi precious gem stones are often treated to artificially boost the color and clarity and to add volume to the gem. Staining, heat treatment, and irradiation are the most popular forms of treatments.Agate is stained a variety of colors: red, yellow, green, blue. Heat treatment of gems to improve or change color has been known to man and used for centuries. When heated, quartz can be made to resemble citrine or topaz, zircons can be made to becomes bright blue or colorless, yellow topaz can be turned to pink, color intensity of most of the semi precious stones can be enhanced. Rubies or amethysts which naturally have color variation are made more evenly colored.
Irradiation is another way to enhance quality of gemstones. It is effective in bringing about color change in gems. Even colorless gems gain their respective colors from the radiation. There is a downside to this treatment though as these colors are not permanent and the gems lose their color after some time besides the probability of the gems becoming radioactive is always there.