What is a gemstone?
Most of the gemstones have a mineral origin, but gemstones such as pearls, coral and ivory have an organic origin. Minerals are natural, not organic materials, with a specific chemical composition of a characteristic structure.
Substances such as bones, seeds and hair are used in jewellery, but do not fall into the category of precious stones. Such substances should have three characteristics to fall into the category of precious stones:
- - beauty
- - rarity
- - durability
Each property has its own range, so the categorization is done by levels.
Beauty is not easy to categorise, as it is different in the eye of every individual. The beauty will cause a visual stimulus for an individual who looks at a particular subject and not every individual will be equally responsive. Concerning the gemstones, visual stimulus will result in a combination of different factors:
- - colour
- - symmetry
- - surface appearance
The most important factor for coloured stones is the colour, which is noticed first. The colour ranges from deep green of an emerald to changing colours of an opal.
Symmetry, the second factor, represents a harmony of cut. Certain parts of the cut increase the beauty of a gemstone because the stone is the most desirable when its form and proportions are in balance.
Rarity is also a part of the scale. Some stones are rarer than the others. A few are so rare that they are considered collectors’ items. Most of the gemstones are ranged in the middle of the rarity scale. Rarity is not a measure of a value of a gemstone. For example, a pink spinel is beautiful, durable and rare. Despite its perfection, the customers are not very interested in it because they are not too familiar with it. Requirements are also unpredictable. Amber was highly regarded in previous centuries, but today, only exceptional examples can attain higher prices.
Marketing can also have a big impact on customers. Representing a stone using an intensive publicity campaign allows easier entry into the market. It doesn’t’ matter how strong and intensive a commercial about a gemstone is, the gemstone must be beautiful and durable, as well as rare, to remain in customers’ consciousness to achieve a desired success.
Durability is a combination of three factors:
- - hardness
- - resistance
- - stability
Hardness is measured by Mohs’ scale from 1 to 10 and is determined by scratching a mineral.
Resistance is the ability of a stone to withstand cutting and splitting. Hardness and resistance are two different factors. For example, a topaz is a relatively hard stone, but it is not resistant.
Stability is measured by resistance of a stone to light, heat and chemicals. Low durability is the reason why beautiful minerals, such as calcite and fluorite, are not used in jewellery. They can be polished and many people may agree that they are pretty, but they have low hardness and poor resistance. Therefore, they are rarely used in jewellery.
 Fluorite |
 Calcite |
