|Gemstones come in a variety of shapes, colors and sizes. They are naturally occurring crystalline forms of some minerals. Precious and semi-precious stones used in jewelry making are specially cut and polished. Some beautiful rocks are also used to make attractive jewelry articles but they are not considered precious gems. The value of a stone is determined by a few factors including its hardness, luster and rarity. Many stones are naturally transparent; however, inclusions of fibrous minerals sometimes make them opaque. The value of diamonds is not measured in the same manner. Almost all stones are graded using the naked eye with the exception of diamond.
Gems are classified as precious and semi-precious. Pearl is considered a precious stone in addition to diamond, ruby, sapphire, opal and emerald. Other stones like peridot, garnet, catís eye and some others are commonly used in jewelry making. Some stones are very rare, for example black opal, apophyllite, epidote, fluorite, rhodizite, etc. These stones are expensive because they are seldom found. Rhodizite is a light yellow stone obtained from Madagascar and is available for $500/carat which is quite expensive. Rarity is one of the most desired qualities of stones.
Gemstones are identified by their chemical composition. The same gem can exhibit different colors because of addition of impurities but the basic chemical composition does not change. They also differ in their colors and hardness based on the location from where they are obtained. For example, emerald occurs in different shades of green. Some emeralds also exhibit bluish tint due to addition of some elements such as chromium. It is also known as a variety of beryl which is short for beryllium aluminum silicate. Aquamarine and morganite are also varieties of this mineral. Beryl exhibits a six-sided or hexagonal crystal shape and its transparency ranges from transparent to opaque.
The mineral quartz also occurs as many varieties including amethyst, rose quartz, chalcedony and citrine. It is found in white, purple and brown colors. It is also known as silicon dioxide or silica. Rose quartz is very beautiful and is often used for making attractive contemporary jewelry articles for women. Addition of titanium and iron to quartz imparts pale pink color to this mineral. Many gemstones occur as varieties of chalcedony including agate, carnelian, heliotrope, and chrysoprase. Agate is further categorized as pure agate, moss agate and onyx. Heliotrope is also known as bloodstone and is considered a mystical birthstone for the month of March.
Some organic materials are also considered as gemstones, such as amber. Amber is a resin and occurs in a beautiful yellow or orange color. It was used as a decorative item in ancient times. Handmade amber jewelry is still very much appreciated in all parts of the world. Cognac amber rings are exchanged on engagements as tokens of love and commitment. Antique amber rings and pendants are also very popular. You can find such a pendant for as low as $34 which is quite reasonable. Amber is often combined with other stones and crystals to enhance its beauty and vigor.
Article Source: ActuaFreeArticles.com