Gemstones come in every color and shade under the sun. Through time, a few of these gemstones have become considered precious gemstones through their color, beauty, rarity and durability.\nSome features of gemstones are the same regardless of whether the gemstone is a sapphire, a ruby or an emerald and so firstly we will look at the aspects of jewelry gemstones which are universal to all gemstone types:\n \nColor\nThe color of a gemstone is determined by how it absorbs and reflects light energy. The different materials and impurities which make up gemstones each absorb and reflect light differently which is why each individual gemstone type is a different color.\n Why gemstones are colored\nIn some gemstones, the color is caused by an essential component of the gemstone meaning the gemstones only occur in that color. An example of this is peridot, the composition of which includes iron sulfide with the iron component responsible for creating the vivid green color in the gems.\n \nIn some other gemstones, the color is caused by impurities in the gemstone material and so these gemstone can occur in different colors created by different impurities. An example of this is sapphires which can be found in colors ranging from pale yellow to deep blue. Blue sapphires are caused by iron and titanium impurities, whereas yellow and green sapphires are caused by iron impurities alone.\n How to describe color gemstones\nWhen the color of gemstones is described, it is usually referred to by three distinct terms: hue, saturation and tone:\nHue is the basic color of the gemstone. Saturation, which is sometimes called color purity or intensity, means the vividness, brightness or colorfulness of the hue of the gemstone. Tone is the amount of color and covers the range of lightness to darkness of the hue.\nThe most highly prized gemstones are often those with a vivid and pure, strong toned, hue.\n \nCut\nThe cut of a gemstone refers to two aspects of the gemstone. The first is how well the gemstone has been cut to enhance the shine or sparkle and color of the gemstone. The second relates to the shape into which the gemstone has been cut.\n Cabochon Cut\nColored gemstones are sometimes cut using a style called a cabochon cut which means they are given a flat base and a smooth domed upper surface. This type of cut is favored for color gemstones which are opaque, for example turquoise; those which are patterned, for example agate, or those that are heavily include such as star sapphires, which are sapphires included with rutile which, when cut, shows as a glittering six point star.\n Faceted Cut\nColored gemstones, particularly transparent colored gemstones, are more commonly cut as faceted gemstones. There are two main types of facet which can be used, namely brilliant cut facets, where each facet is a triangle or a kite shape, or step cut facets where the facets are cut parallel to each other. In some cases, only brilliant cut facets or step cut facets are used however some gemstones are also mixed cut stones, with a mixture of brilliant cut facets and step cut facets used.\n Cut Gemstone Shapes\nThe most common modern cut gemstone shapes are:\n\n \nCarat\nA carat is a unit of weight measurement which is used when determining the weight of gemstones and diamonds. One carat equals 200mg. A carat can also be sub-divided into 100 points, so 1 carat = 100 points. Larger gemstones are generally much rarer than smaller gemstones so the price of gemstones typically increase as the carat weight increases.\n \nAs different gemstones are made up from different materials, which differ in density, the size of a gemstone of a particular carat weight can vary between different gemstone types. Therefore, two gemstones that appear to be the same size may actually have very different carat weights. For instance, a sapphire is more dense than a diamond, so a one-carat sapphire will look smaller than a one-carat diamond. Let's use 6mm round shaped stones as examples :\n \nClarity\nThe clarity of a gemstone is a measure of any flaws found within the cut gemstone. Surface flaws are called blemishes and internal flaws are called inclusions. The flaws may include cracks or fissures, bubbles of gas or other materials or minerals caught within the gemstone as it formed.\n \nFor diamonds, the clarity of the cut stone is very important. However, for colored gemstones, the clarity of the gemstone isn't such an important factor. For example, whilst a very clear rich blue or pink sapphire may be very desirable, a blue sapphire with many rutile inclusion (also known as silks), which create a cats eye effect, can be every bit as desirable and valuable.\nFurthermore, a beautiful bright cornflower blue sapphire which has a few inclusions may be worth much more than a drab grey blue sapphire which has no inclusions. In addition, some very beautiful and valuable colored gemstones, such as pearls or turquoise, are completely opaque. Therefore, for color gemstones, the clarity of the gemstone is a factor which is only relatively important.\n \nGemstone Hardness\nGemstones are rated in hardness using a scale called Moh's scale where 1 is the softest stone and 10 is the hardest. Diamonds are the only gemstones which have a hardness of 10 with all other gemstones being softer than diamonds. The different hardness of color gemstones means that there are some which are more suited to certain types of jewelry than others.\n \nFor example, sapphires and rubies have a hardness of 9 and so, similarly to diamonds, these are very hard stones. This means that sapphires and rubies are perfect for use in a ring as they do not scratch easily and can withstand daily wear and tear. However, a gemstone such as apatite, a beautiful clear asparagus green color gemstone, which has a hardness of 5, is relatively soft and could be scratched easily by a steel kitchen knife for example. This means that apatite is far too soft for use in a ring, as it would easily be damaged but if used in earring or a pendant, it would look stunning.\n \nTherefore when choosing color gemstone jewelry, it is worth considering what type of wear the jewelry will get and whether the gemstone is hard enough to withstand that type of wear.