gemstones

gemstone is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments. However certain rocks, (such as lapis lazuli) and organic materials (such as amber or jet) are not minerals, but are still 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 until the 19th century engraved gems and hardstone carvings such as cups were major luxury art forms; the carvings of Carl Fabergé were the last significant works in this tradition.

Cutting and polishing :

A few gemstones are used as gems in the crystal or other form in which they are found. Most however, are cut and polished for usage as jewelry. The picture to the left is of a rural, commercial cutting operation in Thailand. This small factory cuts thousands of carats of sapphire annually. The two main classifications are stones cut as smooth, dome shaped stones called cabochons, and stones which are cut with a faceting machine by polishing small flat windows called facets at regular intervals at exact angles.

Stones which are opaque such as opal, turquoise, variscite, etc. are commonly cut as cabochons. These gems are designed to show the stone's color or surface properties as in opal and star sapphires. Grinding wheels and polishing agents are used to grind, shape and polish the smooth dome shape of the stones.

Gems which are transparent are normally faceted, a method which shows the optical properties of the stone's interior to its best advantage by maximizing reflected light which is perceived by the viewer as sparkle. There are many commonly used shapes for faceted stones. The facets must be cut at the proper angles, which varies depending on the optical properties of the gem. If the angles are too steep or too shallow, the light will pass through and not be reflected back toward the viewer. The faceting machine is used to hold the stone onto a flat lap for cutting and polishing the flat facets. Rarely, some cutters use special curved laps to cut and polish curved facets.

When shopping for gemstone jewelry :

The world of gemstones is vast, fascinating, and at times intimidating. When we are shopping for gemstones, there is a lot to know. Sometimes we want something beautiful and valuable for ourselves, sometimes we want to give a special gift to someone else. Whatever the case, we gemstone shoppers want to make sure that what we are buying is as valuable as we think it is. This means that we need to learn about the different kinds of gemstones and how much they usually cost. We need to learn about gemstone treatments and imitations. And an especially important task is understanding why pieces of gemstone jewelry can be worth very different amounts even though they contain the same gemstones.

There are many factors that influence the value of gemstones. When shopping for gemstones, it is important to understand these factors. The most common ones are color, clarity, size and cut. Most of these factors have an impact on most gemstones, but on some more than others. Each of the most popular gemstone has several pages of information dedicated to it. You can compare different gemstones you are interested in and if you read all the information presented here, you’ll know everything you need to know to make an educated, informed purchase.

sources and references

wikipedia.org

shopgemstones.com