Like diamonds, there are many factors that affect the quality of a gemstone. Let us study each of these factors in detail and understand how they help us judge the gemstone’s quality.
For every gem variety, colour is the most important value factor which is evaluated in a similar way for each gem. The jewellery industry recognizes the quality of gemstones by these three components of colour:
- Hue: Hue is described as the shade of a colour.
- Tone: Tone is the relative lightness or darkness of a hue.
- Saturation: Saturation refers to the degree to which the gem is free from brown or grey hues. The most desirable gemstone which shows least grey or brown is often described as having vivid or strong colour saturation.
Gemstones come in all possible colours of the spectrum, but also one gemstone itself can come in variety of different hues and shades. Garnet for example, is available in every possible colour, while Sapphires are also available in shades of pink and yellow apart from the usual blue.
Note: Gemstones may have been treated to improve their appearance or durability and may require special care.
The term clarity means purity of a gemstone and freedom from the tiny internal characteristics and impurities that affect the refraction of light rays hence reducing the brilliance of the gemstone. Clarity plays a major part in determining the quality of a gemstone which in turn helps in its evaluation. Pale or pastel shades of gemstones easily show the flaws and are therefore not in demand. Slightly included gemstones fetch a very good amount while flawless gemstones are very rare and hence carry huge prices.
Inclusions and Value: As gemstones are formed by natural process, they may include some impurities within them called as ‘inclusions’. These inclusions are the individual characteristics of every stone and hence are also referred to as ‘birthmarks’. Few inclusions become a part of the gemstone character and add an exotic touch of design to the gemstone. Emerald and Red Tourmaline are seen with such natural inclusion, whereas Citrine, Green Tourmaline and Aquamarine are usually flawless. Very small inclusions are invisible to the naked eye, making the gemstone rare and equally expensive.
Carat Weight and Rarity
Gems are sold by their weight and not by their size. The measurement used to weigh them is carat, which is one-fifth of a gram. Different gemstones have different densities (mass per unit volume), so two gems that appear to be of the same size may actually have different weights. For example, a one-carat Emerald and a one carat Ruby may have same weight but will not have the same size because each is a different mineral with a different density.
Emerald, Ruby, Sapphire and Tsavorite Garnet are some gemstones which rarely are seen in large sizes. Large sizes of these gems demand very high price per carat when compared to its smaller counterparts. Whereas Amethyst, Citrine, Blue Topaz and Amber are easily available in large sizes and therefore quote normal price per carat like their smaller sized stones.
Cut and Beauty
Gemstones are a masterpiece of nature, but it's the skilled hard work of the gem cutter that unleashes its Brilliance (amount of white light returning to the eye from a gemstone) and Beauty (the visual appeal which is a combination of colour, cutting quality and surface appearance).
When we talk about cut we refer to two different things.
The three-dimensional shape it is designed in, e.g. the marquise shape, round cut, oval cut, etc.
The brilliance and beauty reflected by the quality of cutting associated with the precisions of the angles and proportions of workmanship. It is the way a gemstone reflects light and captures attention.
Symmetrical cuts and colourful light reflections with no dark or washed out areas represent the ideal characteristics of a good cut while an asymmetrical cut talks of its low quality.
Gemstones are available in an innumerable variety. In fact, some varieties of gemstones like sapphire arrive in many different colours like blue, yellow and so on. Let us study a few popular gemstones in detail.
Turquoise is a semi-precious stone and is greenish-blue in colour. The shining sky-blue colour of the gem is very popular in artistic jewellery. Turquoise is copper aluminium phosphate and it often has blotches running through in a vein pattern called as ‘Turquoise Matrix’ which can be brown, light grey or black.
Ruby is the red variety from the family corundum and its beautiful red color can be accredited to the chrome present in it. Owing to its beauty, bright color and extreme hardness, Ruby commands an important position in the world of gemstones. It is the birthstone for the month of July and symbolizes love, passion and self-esteem.
All varieties of the corundum family, other than Ruby red, are Sapphires. The Sapphire color chart comprises of the famous velvety deep blue to pink, yellow, orange, green, purple and white. It is widely popular due to its beauty, magnificent color, transparency and hardness. This September birthstone symbolizes harmony, beauty and prosperity.
Tourmalines have the most glorious and incomparable color spectrum offering a wide variety of colors and multi-toned stones. Due to such extensive variations, it is a favorite of jewelry designers. It’s excellent wear and tear qualities and hardness makes Tourmaline an easy to look after gemstone.
Citrine is a form of quartz with colour ranging from yellow to orange to brownish orange. Citrine assists in mental awakening and increasing flexibility in the body. Citrine is the birthstone for the month of November and is also known as the thirteenth anniversary gemstone.
Aquamarine is a member of the beryl group of minerals, available from transparent light blue to slightly greenish-blue color and displays eye clean clarity. Aquamarine is the birthstone for the month of March and assists in connecting with the ocean of awareness, creativity and youthfulness.
The term Garnet is used for a group of closely related minerals. Garnets can be found in a wide array of colors like pink, red, purple, yellow, green, etc. Due to the rich color spectrum of Garnets, they keep pace with changing styles and color trends. It is the birthstone for January and symbolizes passion and exuberance.
Emerald is a member of the beryl species of minerals and has a vivid green hue attributed to the amount of chromium in its atomic structure. Emerald is the birthstone for the month of May and enhances one’s fertility and brilliance. It is also the traditional gemstone for twentieth and thirty-fifth wedding anniversary.
This member of the quartz family is found in shades of purple ranging from light lavender to deep purple. A subtle flash of red helps draw attention beyond the conscious mind, to the realm of pure spiritual knowledge. Amethyst is the birthstone for February and the sixth anniversary gemstone.
Peridot is a transparent gemstone ranging from yellowish green to green in colour. The deep coloured variety of Peridot is often used as a substitute for Emeralds. Owing to its resemblance to Emerald and considerable hardness of the stone it holds a strong position in the jewellery industry. Peridot is the birthstone for August.
Determining the value of a gemstone is not an easy task. The various factors that need to be considered while evaluating a gemstone are:
For gemstones, rarity is a sliding scale. The rarer the gemstone the more valued and cherished it is. But it’s not just rarity that makes a gem more valuable. For instance, Tsavorite Garnet is rarer than Emerald, but Emerald's history makes it more sought-after and valuable.
Durability refers to a gemstone's ability to withstand wear, heat and chemicals. Gems that are more durable are more valued, not always though.
Demand for a gemstone influences its value. Some rare gems are relatively unknown and thus get a reduced demand as well as value. Sometimes marketing of these unknown gems leads to a surge in popularity boosting their value. Tanzanite used to be relatively unknown but has become quite popular in recent times.
Enhancement refers to any kind of treatment given to a gemstone other than cutting and polishing, in order to improve its appearance, durability and strength. The enrichment techniques vary with every variety of gemstone.
Commonly used enhancement techniques are:
Bleaching: It is used to lighten or completely remove the colour of the stone.
Coating: The stone is given a coat of film, enamel, foil etc. to improve appearance, alter colour or add other effects.
Dyeing: Dyeing involves use of colouring matter to intensify colour or establish increased colour uniformity.
Laser Treatment: A laser beam is used to reach the deeper inclusions in the stone and alter them.
Irradiation: This is another technique used to alter the colour of the gemstone. It involves use of neutron and other bombardment and/or heat treatment.
Bonding: Bonding refers to the filling of a porous gemstone with a non-coloured substance, usually plastic, to give strength.
Waxing/Oiling: Waxing/oiling is a technique of improving the appearance of a porous stone by the infusion of colourless wax, paraffin or oil in the pores of the stone.
Types of pearls:
Pearls are said to be the most feminine gemstones and considered as priced possessions for their innocent beauty and rarity. The existence of pearls dates back to more than 4000 years ago. But it definitely adds that elegance and sophistication to your appearance till today, be it any type of pearl- Natural or Cultured.
1. Natural Pearls
Natural Pearls, as the name suggests, are formed by nature. When a small particle, typically a parasite or organic matter accidentally becomes embedded in the tissue of oyster or mollusk, the mantle tissues secrete nacre and the nacre building up in layers eventually forms a pearl. Formation of a natural pearl is a purely accidental phenomenon. Natural pearls are 100% nacre.
2. Cultured Pearls
Cultured Pearls are those formed by deliberate intervention of man. The process of formation of cultured pearls is no different from that of natural pearls except that, here the entrance of a foreign particle is not accidental but intentionally done by man. Culturing of pearls gained momentum as natural pearls are rare to find.
Both Natural and Cultured Pearls can be either Freshwater or Saltwater Pearls:
a. Freshwater Pearls:
As their name suggests, Freshwater Pearls find their origin in fresh water bodies such as lakes, rivers, etc. Though, the traditional source of pearls has been oysters which live in saltwater, molluscs that live in freshwaters can also produce pearls. In general, Freshwater Pearls are not as round as Saltwater Pearls and tend to be less expensive than saltwater pearls.
b. Saltwater Pearls:
The cultivating technique used to obtain Saltwater Pearls takes about two and half years with each oyster giving one pearl. These Pearls are therefore more expensive than Freshwater Pearls and are better in quality because the nacre becomes very thick due to prolonged period of pearl formation.
Given below are a few popular types of pearls majorly used in jewellery-making:
When pearls are cultured within an Akoya oyster, usually found in China and Japan, they are called Akoya Pearls. White and cream coloured pearls are most common while lighter shade of pink and silver pearls are also available. Akoya pearls are perfectly round in shape and very small in size, around 2mm to 11mm, owing to its small size oyster. This consistency of shape favours its use in making of jewellery like stud earrings, bracelets and neck pieces.
Black Tahitian Pearl:
Tahitian Pearls are produced by the black lipped oyster in the islands of French Polynesia. The black lipped oyster is huge, resulting in much larger pearl formation. Most black Tahitian Pearls are rarely pure black. Instead they are silver or charcoal or a multitude of colours with the dominant colour being green. Owing to their rarity and high value, Tahitian pearls make a unique gifting option.
The formation of South Sea Pearls takes places in large culturing area and extended growth period. They are generally much larger as compared to other pearls and tend to have a deep and velvety lustre quality. Silver lipped oysters normally produce pearls in white, silver, aqua and blue family of overtones. The gold lipped one develops overtones in champagne, vanilla and deeper golden variety. South Sea Pearls generally retain the highest value of all pearl types.
Imitation Pearls are simply referred as artificial pearls i.e. pearls that are not created from oysters. Thus they do not fall under the category of true Pearls and are very low in quality due to the difference in weight, smoothness and lustre.
Pearl Evaluation Factors
Amongst all the gemstones, pearls carry their own exclusivity, being the only gem produced by a living organism. This being a natural process, it is nearly impossible to find a flawless pearl making it difficult to standardize a grading scale for pearls. As a result there are a number of factors that are to be considered while determining the value of a pearl. These factors are:
The size of the pearl depends on the variety of the pearl you choose. This is because the size of the South Sea Pearl and the Tahitian Pearl can be bigger than Akoya.
Pearls can be largely categorized into three shapes- Symmetrical, Spherical and Baroque. An example of a symmetrical pearl is an oval, while baroque pearls are irregular in shape.
Pearls possess an intense shine called luster which is a combination of surface brilliance and a deep glow. A quality pearl should be bright and lustrous. Any pearl that appears white, dull or chalky is of an inferior quality.
The clearer the surface of the pearl the better is its value. Check for disfiguring spots, bumps or cracks on the surface of a pearl. Quality pearls have a sharp mirror like reflection. Pearls with the smoothest surfaces are of the highest quality.
Nacre is the natural substance that the mollusc secretes to protect its sensitive flesh from irritants such as shell fragments or implanted beads. The thicker the nacre, the better is its quality
Body colour is the dominant colour of the pearl, while overtone refers to one or more translucent colours that overlie the body colour. For example, some pearls that appear white will have hints of pink overtones when examined closely. The third component of pearl colour could be Orient, presence of which looks like a moving iridescence on or just below the pearl's surface.
In order to ensure that your pearls remain beautiful and lustrous, they need to be taken care of with the following tips:
Avoid wearing pearl jewellery when using cosmetics, sprays, perfumes and sun blocks.
Wiping the pearls with a soft cloth will ensure that they are clean and bright.
Always keep your pearl jewellery in a cloth bag or soft jewellery box separated from hand jewellery items, to prevent them from being scratched.
Make sure that you buy your pearls from recognized and trademark dealers.