What is a Semi-Precious Gemstone?
The term ‘semi-precious gemstone’ encompasses gems of many characteristics and all the colours of the rainbow. They are distinguished from precious gemstones such as diamonds, rubies, and emeralds, mainly due to their greater availability. The price and value of an individual stone or class of stones is set by the market and can fluctuate a great deal; what is valuable and precious today can drop in value as new deposits are discovered or increase as the source dries up. Some semi-precious gems, such as amethyst, were once considered precious due to their rarity. New sources of amethyst have increased the supply and reduced its perceived value in the marketplace. However, it would be a mistake to assume that a plentiful supply of raw materials means that semi-precious gems are substandard or diminished in beauty. A well-cut, flawless topaz or aquamarine in an extraordinary setting is every bit as beautiful as any precious gem. Some semi-precious gems, such as tanzanite and alexandrite, are very valuable; jewellery containing paraiba tourmaline is pricier than some diamond jewellery.
A Short History of Semi-Precious Gemstones
Semi-precious gemstones have been used for enhancement and jewellery-making in nearly every culture, dating back thousands of years. The rarity and difficulty in finding and cultivating most gems made them very precious to early civilizations. New technologies, treatment methods, and sources of gemstones have made them more readily available and easier to enhance and finish. Some gems are considered sacred to different cultures and religions due to healing powers they are believed to possess. Jade has been heavily regarded in Asian cultures for its beauty and mystical qualities. Moonstone is widely used in modern paganism. Many other semi-precious gems such as quartz, amethyst, tourmaline, and tiger’s eye are used for the treatment of nervous disorders, arthritis, and depression.
How Gemstones Are Evaluated
The factors that determine the value of an individual stone are the cut, colour, clarity, flawlessness, and size. Due to the variances in the characteristics of gemstones, such as opacity, they can be analysed in the same manner as precious gems or graded like stones. Opaque stones such as opals and jade are graded on a scale of A to AAA, as well as on flawlessness and finish. Here are the main things to look for in a semi-precious gemstone.
The cut of a stone determines value. Cut is not only the shape of the finished stone, but also the surface area. A precision-cut stone with well-proportioned facets produces a finished gem of superior brilliancy, colour, and light reflection.
Clarity refers to the flawlessness of a gemstone, or the absence of marks, inclusions, and blemishes.
Colour is rated by vivacity, intensity, and saturation. A colour that is bright, in the medium range, with no cloudiness is considered the best quality.
A carat is a unit of weight in gemmology. One carat is equal to .200 grams. However, size is not always a determining factor in valuing a gem; a badly cut or coloured large stone with numerous flaws is lower in value than a smaller but more perfect specimen.
A natural stone is more valuable than a stone that is treated to enhance colour. Treatment methods affect the value of a gem as well. Stones that are dyed or filled to hide flaws are of low quality. Heat treating gems to enhance colour creates a lasting bond and permanent colour change.
This is not the same as opacity. Transparency in a gemstone is measured by how much light is diffused throughout the stone; the more transparent a gem, the higher the value.
- Learn that factors that distinguish a quality stone from one that is substandard.
- Remember that pictures are not always a true representation of a piece. Differences in colour or an inability to determine scale can make the decision to purchase a piece more difficult; ask for clarification or additional information when in doubt.
- Know the right questions to ask the seller about the piece of jewellery, and don’t be afraid to ask them. A listing for jewellery should tell the size of the stone, usually in millimetres, as well as the total measurement of the whole piece of jewellery. It should also list the weight of the stone in carats or grams, or the total weight if there is more than one stone. To get a rough measure of the weight of individual gems, take the total gem weight and divide it by the number of gems. A listing for gemstone jewellery should state whether the stone is natural or treated, and the method of treatment. If this information is not listed, send a message asking for clarification before purchase, and get a written appraisal, if available, and certificate of authenticity.
- The setting is important as well. Natural stones are set in a manner that allows the stone to “breathe.” Typically gemstones are prong set in a slightly elevated manner or have a small hole in the setting directly behind the stone.
- Determine if there are any visible imperfections such as inclusions, cloudiness, or other flaws that decrease value.
- Know the different types of settings and closures. A quality gemstone in a shoddy or cheap setting is no bargain, even at a bargain price. A lobster claw or screw closure is generally more secure than a clasp closure. These are the most common types of settings for jewellery:
|10-, 14-, or 24-Karat Gold||This is the percentage of gold present in a setting. Pure gold is 24 karats, while 10- or 14-karat gold is the amount of gold present, mixed with another metal, to make a total karat weight of 24.|
|Gold Filled||This type of setting is made by layering gold over another filler metal; it will have the initials ‘gf’ after the karat weight.|
|Gold Plated||Gold plating is created when an amount of gold between .15 mls and .25 mls is electronically plated over another base metal; the initials “GP” must be stamped on the back or inside of the item.|
|Vermeil||Vermeil is constructed of gold plating over a base of sterling silver.|
|Fine Silver||This is a setting with a content of at least 99.9 percent silver, it is very soft, but relatively tarnish-resistant compared to sterling silver|
|Sterling Silver||Sterling silver is registered at 92.5 percent silver mixed with another metal, usually copper. It is stronger than pure silver, but tarnishes easier.|
|Silver Plated||A base metal with an electroplated coating of between .15 – .25 mls of sterling silver.|
NOTE: Gemstones can also be affixed by wire or thread, usually made of either natural silk or nylon. 7. Buy what excites the eye. Perceived market value is no substitute for the beauty of a well-crafted or unusual piece, regardless of any other consideration.
In the end buying jewellery is a personal experience. What is beautiful to the individual eye is precious to that person. Some types of gemstones have a personal meaning or association and therefore have a greater value to the owner. Armed with knowledge of what to look for in semi-precious gemstone jewellery, the buyer can make an educated decision on finding the best quality and value.