A gemstone (also called a gem, fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments.[1][2] However, certain rocks (such as lapis lazuli and opal) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) are also used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone.
Apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem maker is called a lapidary or gemcutter; a diamond cutter is called a diamantaire.
Gemstones have played various roles in the myths and legends of human cultures throughout history. Some tell a story or are believed to have special powers, but all of them share a common beauty. Each gemstone is unique with a special color, birthplace and story. Gemstones come in every color of the rainbow and are gathered from all corners of the world, with each colored gemstone possessing a unique creation of beautiful color. Some gemstones have been treasured since before history began and others were only discovered recently. Join us as we explore the world of color gemstone jewelry.
Gemstones which are highly valuable for their hardness and rarity, are known as Precious Stones. Precious Stones are generally expensive in comparison of Semi-Precious Stones. There are only four Precious Stones:
Diamond
Diamond is renowned for its superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, it has the highest hardness and thermal conductivity of any bulk material. Most natural diamonds have ages between 1 billion and 3.5 billion years. Most were formed at depths of 150 to 250 kilometers (93 to 155 mi) in the Earth’s mantle, although a few have come from as deep as 800 kilometers (500 mi). Marketing has significantly affected the image of diamond as a valuable commodity.
However, many people expect a diamond to be unbreakable. This is not true. A diamond’s crystal structure has ‘hard’ and ‘soft’ directions. A blow of sufficient force, in an exact direction, can crack, chip, split or even shatter a diamond. The Crater of Diamonds State Park in Arkansas is the world’s only diamond mine open to the public and this is a dig-for-fee operation for tourists and rock enthusiasts. An average of 74,000 visitors comes to the park each year. About one out of 100 visitors find a diamond.
There is no universally accepted grading system for gemstones. Diamonds are graded using a system developed by the Gemological Institute of America (GIA) in the early 1950s. Historically, all gemstones were graded using the naked eye. The GIA system included a major innovation: the introduction of 10x magnification as the standard for grading clarity. Other gemstones are still graded using the naked eye (assuming 20/20 vision).[8]
A mnemonic device, the “four Cs” (color, cut, clarity, and carats), has been introduced to help the consumer understand the factors used to grade a diamond.[9] With modification, these categories can be useful in understanding the grading of all gemstones. The four criteria carry different weight depending upon whether they are applied to colored gemstones or to colorless diamonds. In diamonds, cut is the primary determinant of value, followed by clarity and color. Diamonds are meant to sparkle, to break down light into its constituent rainbow colors (dispersion), chop it up into bright little pieces (scintillation), and deliver it to the eye (brilliance). In its rough crystalline form, a diamond will do none of these things; it requires proper fashioning and this is called “cut”. In gemstones that have color, including colored diamonds, it is the purity and beauty of that color that is the primary determinant of quality.
Emerald
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