Gemstone Guide
This gemstone guide will help you get started gemstone shopping. First, you need to have an in-depth understanding of what you’re buying. This gemstone guide expands your knowledge on gemstones, so you can select your gemstones based on the same criteria that jewelers use to grade them.
Introduction to Gemstones
A gemstone is a mineral or rock which can be used in jewelry after cutting or faceting and polishing. Gemstones are an important commodity in today’s marketplace. They have been sought after for thousands of years for their beauty, metaphysical properties, and commercial uses. In earlier times there were no such things as synthetic gemstones but today they are quite common.
Gemstones are diverse in their beauty and many gems are available in a stunning variety of colors. Most gemstones have little beauty in the rough state. They may look like ordinary rocks or pebbles. After a skilled cutting and polishing of a gem, full color and luster can be seen.
The 5 Formation Categories of Gemstones
Natural Gemstones
These have been formed in nature with no interference by humans. They form in a variety of ways in many different environments from many different chemical compounds. By the time they appear in our jewelry they’ve been cut or polished, but they’ve not been treated or altered in other ways.
Genuine Gemstones
Genuine Gemstones are nothing but natural gemstones which are treated in some way to enhance its appearance. A large percentage of natural gemstones are treated to enhance their appearance for jewelry manufacturing.
Synthetic Gemstones
A synthetic gemstone shares a natural stone’s physical, chemical and optical qualities, but it is created in a laboratory. More recently, synthetic versions of nearly all popular gemstones are available. Some modern synthetic gemstones look more natural and are more difficult to identify, but an experienced jeweler or gemologist can usually detect them. Jewelry that includes quality synthetic gems can be just as beautiful as jewelry made with natural stones.
Imitation or Simulated Gemstones
Imitation gemstones can be anything that resembles a natural gemstone but does not have the same physical characteristics or chemical composition. These items are usually much less expensive than the natural forms. Imitation stones are often made of glass or plastic and most can be detected easily by a jeweler.
Treated Gemstones
A number of techniques are used to improve the color and appearance of natural and synthetic gemstones. Gemstone’s beauty is enhanced, to increase the desirability and demand of the gemstone. Probably the oldest method is that of heat treatment for gemstones to improve or change the color. As a result of recent advances in technology, there are now many different techniques, which use modern equipment such as lasers, and computer controlled heating and irradiating procedures. Lasers are used to drill holes into stones to reach inclusions. These are then evaporated or removed using chemicals before the crack is filled. Some treatments are permanent such as drilling while others are temporary. For example, stains and fillings may leak, some heated, and irradiated stones may fade or revert to their original color.
Gems manage to endure through time because of their certain characteristics.
Characteristics of Desirable Gemstones
Beauty & Appearance
A gemstone is prized especially for great beauty or perfection so appearance is almost always the most important attribute of gemstones. A gemstone’s beauty will depend on its Color, Size, Shape and Sparkle. Color is the most important gem characteristic whereas Size and Shape also have a huge role in enhancing the beauty of gemstone. Gemstone’s Sparkle enhances its beauty in a great manner. In a way, all stones reflect light from their surface and ideally all the light entering the stone from any angle would escape via the top (front) of the stone.
Durability & Hardness
Durability and Hardness are other aspects which are considered as important characteristics of a gemstone. Regardless of how beautiful a stone may appear, for it to be suitable as a gemstone, it will need to be reasonably durable and hard. There are numerous different ways of considering hardness, but the main one for gems is their resistance to abrasion.
Rarity
Rarity is also desirable for a gemstone. The rarity of a stone imparts a sense of exclusiveness and worth that increases our desire to possess it. Rarity determines the prices placed on gems and famous jewelry the world over. Gems may be rare for a variety of reasons. Many gems are varieties of common stones, but their exceptional color or clarity determines them to be rare gemstones.
Other Characteristics
Fashion, Superstition and Social Customs also play a part in determining the importance of a gemstone. Today, gemstone jewelry is also worn as a fashion trend. Where as many people also wear gemstones as Superstition and Social Customs. Since ancient times, colored stones have been believed to possess innate magical powers.
Types of Gemstones
From the very dawn of civilization, man has been fascinated by brilliant, shiny, colorful shells, stones and crystals. Their possession made him more important than others. Gems have always been regarded as bringers of peace, prosperity and happiness.
A couple of centuries ago, the terms ‘Precious’ and ‘Semi-Precious’ stones came into common use. Although there are many exceptions to this classification, these terms are still in use. For example, diamonds have always been considered precious stones, yet there are diamonds that sell for $100 a carat. On the other hand, there are garnets that sell in excess of $1,000 a carat and garnets have traditionally been considered semiprecious stones. For this reason, jewelers may often refer to gemstones other than diamond, as ‘Colored Stones’.
The 2 Categories of Gemstone Types
Precious Stones
Gemstones which are highly valued for their beauty, hardness and rarity are known as precious stones. Precious stones are generally expensive in comparison to semi-precious stones. There are only four precious stones:
Diamond
Diamond is described extensively in the Diamond Guide.
Emerald
Color – Emerald Green to Dark Green
Mohs hardness scale – 7.5 – 8
Mineral Class – Beryl
Source – Found in Columbia, Brazil, Zimbabwe, South Africa, Afghanistan, USA
Emerald is a fascinating and beautiful gemstone. The name of this remarkable gemstone comes from Greek ‘Smaragdos’, meaning ‘Green Stone’. It’s beautiful green color, combined with its durability and rarity, makes it the one of the most valuable gemstones. Deep green is the most desired color in emeralds. The green color of this stone holds a mystic meaning in many cultures and religions.
Although emeralds are notorious for their flaws, these gems have been held in high esteem since ancient times. Flawless stones are very uncommon, and are extremely valuable, sometimes even more than diamonds. Its hardness protects the stone, to a large extent, from scratches, but it may develop internal cracks if banged hard or if exposed to extreme temperature. Emeralds that were treated to mask internal flaws should never be cleaned with an ultrasonic jewelry cleaner, nor should they be washed with soap. These practices will remove the oil and expose the hidden internal flaws.
Ruby
Color – Bright red, brownish-red, purplish-red, dark red
Mohs hardness scale – 9
Mineral Class – Corundum
Source – Found mainly in Burma, Thailand, Sri Lanka and Tanzania
Ruby is the red variety of the mineral corundum, one of the hardest minerals on Earth. Sapphire is also a variety. Corundum is the mineral form of aluminum oxide. Only red corundum is entitled to be called ruby, all other colors being classified as sapphires. The most prized tint is blood red or crimson known in the trade as ‘pigeon’s blood’ red.
The name of this rich and noble gemstone comes from Latin ‘Ruber’ for ‘Red’. In Sanskrit, the ruby is called ‘Ratnaraj’, means ‘the king of precious stones’. For thousands of years, the ruby has been considered one of the most valuable gemstones on Earth. It has everything a precious stone should have: magnificent color, excellent hardness and outstanding brilliance. In addition to that, it is an extremely rare gemstone, especially in its finer qualities. The most important thing about this precious stone is its color. The red color of the ruby is incomparable: warm and fiery. Transparent rubies of large sizes are even more rare than diamonds.
The ruby is considered an excellent choice for the jewelry. Beyond its incomparably rich red hue, which alone might be enough attraction, the ruby is second only to the diamond for strength and durability. Although Ruby is a tough and durable gem, it is still subject to chipping and fracture if handled roughly.
Sapphire
Color – Blue, Yellow, Green, White, Colorless, Pink, Orange, Brown and Purple
Mohs hardness scale – 9
Mineral Class – Corundum
Source – Found mainly in Sri Lanka, Thailand, Burma, Australia, India, Brazil and Africa
Sapphire is also a variety of the mineral Corundum and represents all the colors except red corundum, which is ruby. Its physical and chemical properties are virtually similar to properties of ruby. Blue is the main color of the sapphire, but this gemstone is also found in colors like green, orange, pink, gray, colorless, black, brown, and purple. The word ‘Sapphire’ in its plain context refers only to blue sapphire, unless a prefix color is specified. Sapphire with a color other than blue is often called a ‘Fancy’ in the gem trade. The sapphire gemstone symbolizes harmony, friendship and loyalty.
Sapphire is the most precious blue gemstone. It is a most desirable gem due to its color, hardness, durability, and luster. The value of this gemstone depends on its size, color and transparency. Top-quality sapphires are extremely rare. Cutting this gemstone requires great skill and experience. It is the job of the cutter to orientate the raw crystals in such a way that the color is brought out to its best presentation. Both sapphires and rubies have been successfully and widely produced synthetically in laboratories. In appearance, chemical composition and hardness they are almost identical to the natural gems. France is the major production hub for synthetic corundum.
The sapphire is also considered an excellent choice for jewelry. In terms of hardness and durability, it is second only to the diamond (and equal to the ruby). It can be worn every day as opposed to more fragile gemstones like the opal or topaz. Although sapphire is a hard and durable gem, it is still subject to chipping and fracture if handled very roughly.
Semi-Precious Stones
Gemstones that are valued for their beauty and not covered under any one of the four ‘precious stones’, diamond, emerald, ruby or sapphire, are known as semi-precious stones. Semi-precious stones are available in all price ranges from low to high. There are many semi-precious stones:
Alexandrite
Color – Dark to Pale Green (color changes in different forms of light)
Mohs hardness scale – 8.5
Mineral Class – Chrysoberyl
Source – Found mainly in Russia, Sri Lanka, Brazil, Burma, Madagascar, USA
Alexandrite is a form of the mineral Chrysoberyl, discovered in 1830 in Russia and named after Czar Alexander II, who was then Crown Prince of Russia. This is a very attractive and rare stone, and therefore finely faceted Alexandrite above one carat is among the most expensive gemstones in the world, more rare than fine ruby, sapphire or emerald.
The most sensational feature about this stone is its surprising ability to change its color under different forms of light. Green or bluish-green in daylight, red in candle light, green in fluorescent light and reddish-purple in standard electric (tungsten) light.
Amethyst
Color – Purple, Pale lavender to deep reddish purple, bluish violet
Mohs hardness scale – 7
Mineral Class – Quartz
Source – Found mainly in Sri Lanka, Brazil, Burma, Canada, East Africa, India, North America, Russia, Uruguay, Madagascar and Australia
Amethyst is a variety of the Quartz family, colored by traces of manganese, titanium and iron. Deeper-colored amethysts are more highly valued. Rich purple has always been a rare and noble color. Amethyst’s name comes from Greek word ‘Amethystos’ mean ‘Not Intoxicated’ or ‘Not Drunken’. The amethyst is said to bring good luck and to radiate love. This brilliantly sparkling stone is the most valued gemstone from the quartz family.
Aquamarine
Color – Blue, Sea-green
Mohs hardness scale – 7.5 – 8
Mineral Class – Beryl
Source – Found mainly in Brazil, Madagascar, Russia, Afghanistan, India, Pakistan, Nigeria, Zambia, Mozambique and USA
Aquamarine is a variety of the mineral Beryl. This is a fascinatingly beautiful gemstone found in colors like the light blue of the sky to the deep blue of the sea. The more intense the color of an aquamarine, the more value is put on it.
Its name is derived from the Latin ‘Aqua’ (water) and ‘Mare’ (sea). Aquamarine is one of the most popular and best-known gemstones. Its hardness makes it very tough and protects it to a large extent from scratches. There is hardly any other gemstone in modern jewelry design which is refined in such a variety of ways as aquamarine.
Citrine
Color – Light Yellow, Lemon Yellow, Amber-Brown, Brilliant Orange
Mohs hardness scale – 7
Mineral Class – Quartz
Source – Found mainly in South America, Brazil, Madagascar, Argentina, Russia, Scotland and Spain
Citrine is a variety of the mineral Quartz and is often mistakenly called ‘Topaz’. This radiant, lemony yellow gemstone gets its name from the French word ‘Citrin’, meaning ‘Yellow’. There are not many yellow gemstones in the world of jewels and the citrine fulfils everyone’s color wishes, from lemon yellow to reddish brown, in an affordable price range.
Citrine is known as a tough gemstone with good durability. To a large extent, citrine is insensitive to scratches and thus it is an excellent choice for everyday jewelry.
Garnet
Color – Light Red, Violet, Red, White, Green, Yellow, Brown, Black
Mohs hardness scale – 6.5-7.5
Mineral Class – Quartz
Source – Found mainly in Burma, Sri Lanka, South Africa, China, USA, Tanzania, Madagascar, India and Australia
Garnet is a family of stones having many varieties differing in color and in their constituents. The name is derived from its resemblance in color and shape to the seeds of the pomegranate. This stone has a long history of use as a medicinal stone and was used for healing blood and lung diseases. The most common color of garnets ranges from light red to violet, but can also be white, green, yellow, brown and black.
Garnet stones include the following varieties:
Grossularite
Grossularite is generally olive green, but there are also yellow, red, brown and violet varieties.
Pyrope
Pyrope is similar to Almandine, but is lighter in color and brighter, even though it is translucent. It is often mistaken for ruby.
Almandine
Almandine is a deep velvety red and the most widely used in jewelry making. The best stones are those that are not too dark.
Rhodolite
Rhodolite is half-way between Almandine and Pyrope, being of a rhododendron red color, and is the most prized of the garnets. The fire of top-quality rhodolite is excellent.
Other varieties
• Andradite
• Essonite
• Tsavorite
• Spessartite
• Melanite
• Allochroite
• Ouvarovite
• Demantoid
Iolite
Color – Violet-Blue, Deep Blue, Light Blue-Gray, Yellow-White
Mohs hardness scale – 7 – 7.5
Mineral Class – Cordierite
Source – Found mainly in India, Sri Lanka, Mozambique, Zimbabwe and Brazil
Iolite The name Iolite comes from the Greek word ‘Ion’, which means ‘Violet’. Iolite is often confused with tanzanite because of its similarity in color. Generally, iolite is a deeper shade of violet, with hues ranging from deep blue, purple, lavender, and gray-blue.
This gem was actually used as a navigation tool by Viking explorers. Thin pieces of iolite were cut and used as polarizing filter lenses. Looking through the lens, they could determine the exact position of the sun and use it to guide them to the New World and back.
Iolite is relatively hard but should be protected from blows. With its attractive color and reasonable price, it may become a jewelry staple in the future.
Onyx
Color – Black, White, Black with White bands, Red, Brown
Mohs hardness scale – 6.5 – 7
Mineral Class – Quartz
Source – Found mainly in Madagascar, India, Brazil, United States, Pakistan and Sri Lanka
Onyx is a beautiful gemstone composed of chalcedony (a variety of quartz). This gemstone usually comes in white, black or black with white bands and it is generally dyed black to improve its color. The bands that are found on Onyx run parallel and are consistent. It is extremely similar to Agate, another variety of quartz. Agate bands are round or circular and are not consistent. Onyx that is available in a red, brown or reddish-brown color is known as Sardonyx.
Onyx was very popular with the ancient Greeks and Romans. The name comes from the Greek word ‘onyx’, which means nail or claw. In fine jewelry, the black backdrop is often supplied by onyx. Black Onyx gemstones with white bands are generally used in cameos and beads.
Opal
Color – Black, White, Gray, Yellow, Red, Orange and Colorless
Mohs hardness scale – 5 – 6.5
Source – Found mainly in Australia, Brazil, Mali, Japan, Russia, USA, Mexico
Opal is a very popular gemstone, mainly due to its wonderful variety of rich and beautiful colors. One of the extraordinary features of this gemstone is called opalescence. Opalescence is a kind of light play that happens with certain high-quality stones. Light reflects and bounces around the very small structures of the stone, giving it a wonderful aura and sometimes iridescence.
The name Opal is derived from three sources: Sanskrit ‘Upala’, Latin ‘Opalus’, and Greek ‘Opallios’. All three of these words mean the same thing – precious stone. The group of fine opals includes quite a number of wonderful gemstones. These gemstones are differentiated on the basis of the variety, place of occurrence, and color of the main body, into dark or black opal, white or light opal, milk or crystal opal, boulder opal, opal matrix, Mexican and fire opal.
Opals come in many colors, including black, white, gray, yellow, colorless, orange and red. Red is considered the most popular and attractive color that Opal comes in. There are usually two types of red colors – cherry red and fire red. Fire red is usually the most popular and possibly the most expensive due to its wonderful hue.
Australia is the major supplier of fine opals and almost 95 per cent of all opals come from Australian mines. Opal is made from sand and water. It has the same chemical formula as quartz with the addition of 3-10 % water content. Due to this reason, opals must be protected from harsh light and heat, which could dry it out and cause cracks. Opal is relatively less hard than many other stones and must be worn with caution and care taken to avoid chips or other breakage. Opals come in many attractive colors, shapes and sizes and are used on many types of ornamental jewelry including rings, earrings, brooches, charms, bracelets, etc.
Pearl
Color – White, White tinted with Cream, Pink, Yellow, Green, Blue, Brown, Purple, or Black.
Mohs hardness scale – 2.5 – 4.5
Source – Found mainly in Persian Gulf, China Sea
A Pearl is an organic gem, produced when certain mollusks, primarily oysters cover a foreign object with beautiful layers of nacre. A good-sized pearl can take between five to eight years to form, which is usually the entire life of the oyster or mollusk.
There are two types of pearls: natural pearls, formed inside wild oysters, practically impossible to find nowadays, and cultured pearls in which the production of the pearl is artificially induced. For producing cultured pearls, shell beads are placed inside an oyster and the oyster is returned to the water. When the pearls are later harvested, the oyster has covered the bead with layers of nacre. The finest natural pearls are fished almost exclusively from the Persian Gulf and the China Sea, while the best cultivated ones come from Japan, Korea and more recently Australia. Fine natural pearls are much more expensive and more difficult to find than cultured pearls.
Pearls are usually white, sometimes with a creamy or pinkish tinge, but may be tinted with yellow, green, blue, brown, purple, or black. Pearls are available in different shapes: round, semi-round, button, drop, pear, oval, baroque, and ringed. Perfectly round pearls are the rarest and most expensive. Pearl is a rare and living substance and should be treated with great care.
Peridot
Color – Yellow Green, Olive, Brownish Green
Mohs hardness scale – 6.5 – 7
Mineral Class – Olivine
Source – Found mainly in Australia, Mexico, Sri Lanka, South Africa, Tanzania, China, Burma, Arizona, USA, Pakistan, Afghanistan
The Peridot is a very old but still very popular gemstone. It is a variety of the mineral olivine. The color of most gemstones is caused by traces of other elements, but the color of peridot is an integral part of its structure. Chemically, peridot is an iron-magnesium-silicate. The intensity of the color of the stone depends upon the amount of iron contained. The beauty of peridot is a result of extreme conditions. Peridot is formed deep within the earth under tremendous heat and pressure.
This gemstone is in fact identified by three names, Peridot, Chrysolith and Olivin. ‘Peridot’ is derived from Greek word ‘Peridona’, which means ‘giving plenty’. The word ‘Chrysolith’ means ‘goldstone’ in Greek. It is one of the few stones that exist only in one color. The most beautiful peridot comes from Pakistan-Afghanistan border region. It is also found in Australia, Mexico, Sri Lanka, South Africa, Tanzania, China, Burma, Arizona and USA. Peridot is used in rings, earrings, pendants, bracelets.
Tanzanite
Color – Deep Blue, Ultramarine Blue, Light Violet-Blue, Purple
Mohs hardness scale – 6 – 7
Mineral Class – Quartz
Source – Found in Tanzania
Tanzanite is an extraordinary and beautiful gemstone. Tanzanite is a blue variety of the gemstone zoisite, discovered in 1967 at Merelani Hills in Tanzania. It is named after the East African state of Tanzania, the only place in the world where it has been found. Due to this reason, this stone is particularly highly prized.
Tanzanite is a trichroic gem which displays three layers of color. The colors dark blue, green-yellow and red-purple can be seen. Nearly all tanzanite has been heat treated to generate the beautiful violet-blue color this stone is known for.
Although Tanzanite is relatively new on the gemstone market, it has left its mark. Tanzanite is popular for its brilliance and is a widely distributed gemstone. At the same time, Tanzanite is a delicate gemstone and it should always be worn carefully. Never clean tanzanite in an ultrasonic cleaner or resize or repair a Tanzanite ring set without having the gem removed because the stone could shatter in the heat of a torch.
Topaz
Color – Blue, Brown, Green, Orange, Pink, Red, Yellow, White, Gold, Colorless
Mohs hardness scale – 8
Mineral Class – Topaz
Source – Found mainly in Brazil, Sri Lanka, Burma, Nigeria, USA, Australia, Madagascar and Mexico
Topaz is a member of the Quartz family. This beautiful gemstone is most commonly found in a yellow color. A topaz turns a vivid blue when exposed to heat. Also, the Topaz is said to have the power of changing color when it’s near poison. The name topaz is derived from the Sanskrit word ‘Tapas’, meaning ‘Fire’.
Although Topaz is considered to be a tough and durable gemstone it is not an invincible stone. It cracks and chips more easily than many other gemstones, and should be treated with care.
Tourmaline
Color – Black, Red, Pink, Blue, Green, Grey and Yellow
Mohs hardness scale – 7 – 7.5
Mineral Class – Quartzite
Source – Found mainly in Brazil, Sri Lanka, South Africa, Nigeria, Zimbabwe, Kenya, Tanzania, Mozambique, Madagascar, Pakistan, Afghanistan, USA
Tourmalines are gemstones with deep brilliance and an incomparable variety of colors. These gemstones are mixed crystals of aluminum boron silicate with a complex and changing composition.
The name tourmaline comes from the Singhalese word ‘ turamali’, means roughly ‘stone with mixed colors’. Tourmalines with different colors have different names. For example, a tourmaline of an intense red is known as a ‘rubellite’, but if it changes color at a change in the light source then the stone is called pink or shocking pink tourmaline. Stones with two colors are known as bicolored tourmalines, and those with more than two are known as multicolored tourmalines.
This gemstone has excellent wearability qualities and is easy to take care of. No two tourmalines are exactly alike. In the fascinating world of gemstones, the tourmaline has a very special place.
5 Essential Characteristics of Gemstones
Color
The color of a gemstone is its most significant characteristic, and many jewelers consider it to be the most vital evaluation criterion. Gemstones are found in all colors. The color of a gemstone depends on following three characteristics: hue, saturation, and tone.
Hue
The Hue is the basic or unique color of the gemstone, it is described as the shade, tint or sensation of color. While almost all gemstones have some shades of other colors, the most valuable gemstones are those that exhibit a pure color and only ‘slight’ hues of other colors in addition to their primary color.
SATURATION
Saturation is a measure of the intensity or purity of a gem’s hue or color. A gemstone that is free of gray or brown hues is considered to be strongly saturated and is more valuable than a gemstone with lower saturation. Saturation often decides the cut of a gemstone. A high-quality gemstone cut delivers an even color throughout the stone and exposes the fewest inclusions.
TONE
Tone represents the depth of a gemstone color, ranging from colorless to black. In other words, tone is described as the relative lightness or darkness of a hue. Gemstone tone is described as ‘light’, ‘medium-light’, ‘medium’, ‘medium-dark’, and ‘dark’. Medium-light to medium-dark tone is considered to be the most valuable range. All the above three characteristics are associated with each other and play very crucial roles in determining the gemstone’s color. The more intense the color, the greater the value. This does not mean darker, but more intense.
Clarity
Clarity is a term used to describe the absence or presence of flaws inside or on the surface of a gemstone. A flawless gemstone is rare and usually expensive. Most gemstones have inclusions, or tiny mineral flaws, that can be seen under magnification or by the careful eye. A gemstone may have inclusions, cracks, spots, clouds, or any other blemish or imperfection.
For diamonds, a clarity Grade Scale from F (Flawless) to I3 (Included 3) is used, whereas for other colored gemstones a different grading scale is used. Colored stones are classified into three ‘Types’, which are defined as below:
• Type I:
Type I colored stones include stones with very little or no inclusions. This category can include Aquamarine, Blue Topaz, Zircon, Morganite, Tanzanite, etc.
Clarity in the Type I group is classified as VVS (minute to detectable), VS (minor), SI1 (noticeable), SI2 (obvious) or I (included)
• Type II:
Type II colored stones include stones that often have a few inclusions. This category can include Corundum, Garnets, Iolite, Peridot, Quartz (Amethyst, Citrine,
Ametrine), Ruby, Sapphire, Spinel, etc.
Clarity in the Type II group is classified as VVS (minor), VS (noticeable), SI1 (obvious), SI2 (prominent), or I (prominent, affecting appearance).
• Type III:
Type III colored stones include stones that usually always have inclusions. This category can include Emeralds, Tourmaline, etc.
Clarity in the Type III group is classified as VVS (noticeable), VS (Obvious), SI1 (prominent), SI2 (more prominent), or I1 (affecting appearance or durability).
Cut
A good cut is crucial to giving a gemstone its beauty and brilliance. A gemstone’s cut refers to its proportions and symmetry. The stone should be symmetrical in all dimensions so that it will appear balanced, and so that its facets will reflect light evenly, which will provide good brilliance to the stone. A well-cut faceted gemstone reflects light back evenly across its surface area when held face up. If the stone is too deep and narrow, the surface area will be dark and if it is too shallow and wide, parts of the stone will be washed out and lifeless.
While cutting, the color of a gemstone should also be considered for optical efficiency. If a stone’s color is highly saturated, a shallow cut will allow it to pass more light, while a deeper cut may increase the vividness of a less saturated gem. There is no generally accepted grading system for gemstone cut.
Cabochon Cut
These have been formed in nature with no interference by humans. They form in a variety of ways in many different environments from many different chemical compounds. By the time they appear in our jewelry they’ve been cut or polished, but they’ve not been treated or altered in other ways.
Table Cut
In the table cut, the facets of the natural octahedron of the stone are ground to smoothness and polished. One facet, the table, is ground much larger than any other and made the top of the gem, while the opposite facet, the culet, is left quite small.
Rose Cut
The rose cut consists of a flat base and (usually) 24 triangular facets—resembling a cabochon with facets.
Brilliant Cut
The brilliant cut is scientifically designed to bring out the maximum brilliancy of the stone. The crown of a brilliant consists of a table and 32 smaller facets, of which 8 are quadrilaterals and 24 are triangles; the base, a culet and 24 larger facets, of which 8 are quadrilaterals and 16 are triangles. The base and crown are separated by a girdle. The brilliant cut has certain proportions—in general, the depth of the crown is one third the depth of the stone and the width of the table one half the width of the stone.
Other Cuts
In addition to the above defined cuts, stones are also cut in a variety of square, triangular, step, emerald, and trapezoidal faceted cuts. The use of such cuts is largely determined by the original shape of the stone. Large rubies, sapphires, and emeralds are often cut square or rectangular with a large table facet surrounded by a relatively small number of supplementary facets.
The process of cutting and polishing gems is called gem cutting or lapidary, while a person who cuts and polishes gems is called a gem cutter or a lapidary (sometimes lapidarist). Few gemstones such as pearls and coral (usually referred to organic minerals) are not cut at all and many times left in their natural state. However, it is customary to polish these items, as with all gemstones. The quality of a gemstone’s cut can have a dramatic impact on how it looks but only a small impact on the price per carat.
Size
Similar to diamonds, a gemstone’s weight is also measured in carats where one carat equals 200 milligrams. However, in the case of gemstones, this may not give an accurate idea of its size, because different types of stones have different densities Two gemstones of the same carat weight may be different in sizes. For example, a 1 carat Sapphire or Ruby will be smaller than a 1 carat Emerald, though they have the same carat weight because Sapphires and Rubies are denser than Emeralds. At the same time, a 1 carat Diamond will be larger than a 1 carat Ruby as a Diamond is less dense than a Ruby. Gemstones can also be measured in dimensions (diameter, length, and width).
Illustration of gemstone dimensions (L/W = Length to Width Ratio)
Asscher
Baguette
CUSHION
Emerald
HEART
Marquise
Oval
Pear
Princess
Radiant
Round
Trillion
In the case of gemstones, larger stones are not always more valuable. The rarity of a certain size will determine the value of a gemstone. A gem that is available naturally in weights of 10 carats or more may be less valuable than one that is rarely available in large sizes.
Enhancements
All gemstones can be divided into 3 basic categories:
N – The ‘N’ symbol appears on the chart only for natural stones which are not currently known to be enhanced.
E – The ‘E’ symbol appears on the chart only for those gemstones, which are routinely enhanced. The type of enhancement covered by this symbol is indicated on the following chart.
Third category covers those gemstones which are treated in a non-traditional manner and that enhancement process or code is not covered under ‘N’ & ‘E’ symbols.
Gemstone enhancement is a treatment process other than cutting and polishing that improves the appearance (color / clarity), durability or availability of a gemstone. This treatment covers heating, oiling, irradiation, waxing, dying, bleaching etc.
There are many ways to enhance the appearance and durability of gemstones. Some of these treatments or enhancements are permanent whereas others are temporary. Gemstone enhancement has become such a common as well as accepted practice that experts believe the vast majority of stones are treated in some way. It’s important to remember that most gemstone enhancements greatly improve the appearance – and hence the value – of a stone.
Gemstone Enhancement Information
B – Bleaching: The use of chemicals or other agents to lighten or remove a gemstone’s color. Pearls and ivory also may be bleached to lighten their color.
C – Coating: The use of such surface enhancements as lacquering, enameling, inking, foiling, or application of films to improve appearance, provide color or add other special effects.
D – Dyeing: The introduction of coloring matter into a gemstone to give it new color, intensify present color or improve color uniformity.
F – Filling: As a by-product of heat enhancement, the presence of solidified borax or similar colorless substances which are visible under properly illuminated 10X magnification.
G – Gamma/Electron Irradiation: The use of gamma and/or electron bombardment to alter a gemstone’s color; may be followed by a heating process.
H – Heating: Heating is one of the most common treatments used to enhance the natural beauty of colored gemstones. It is a permanent process that can dramatically improve the color and/or clarity in a number of stones, including sapphires, rubies, diamonds, aquamarine, amethyst, tanzanite, topaz, tourmaline and other stones.
I – Infilling: The intentional filling of surface breaking cavities or fractures usually with glass, plastic, opticon with hardeners and/or other hardened foreign substances to improve durability, appearance and/or add weight.
Care
Gemstones are generally hard and durable in nature but given our day-to-day activities, our gemstone jewelry will get dirty and soiled. Gems can be scratched, chipped or dulled if not handled correctly. With proper care, they can last a lifetime and can even be handed down as heirlooms to future generations without losing their shine and sparkle. Organic gems like pearls, amber, and coral require special care because they are porous. Here are some tips that will help you to preserve the life and beauty of your gemstones:
Cleaning of Colored Gemstone Jewelry
Regular cleaning of Gemstone Jewelry is essential to maintain the shine and brilliance of the gems. On wearing them, they get dirty as you use various skin and body care regimen such as soaps, lotions and even our skin’s natural oils. Even when you are not wearing them, they collect dust. If you are cleaning your gemstone jewelry by your own then it will take few minutes to clean the same but before cleaning, you must be aware about the cleaning at home and cleaning by a professional jeweler:
- To clean gemstone jewelry, first wipe it with a soft cloth to remove any dirt. You can use a small soft brush such as an eyebrow or lip stick brush, soap and water
to clean your gemstone jewelry. Do not use toothpaste or any other abrasive cleaner on stones or the mounting. Simply make a bowl of warm sudsy water with a
mild detergent and gently place your jewelry pieces in the mixture. Never use boiling or hot water to clean gems. Brush the gemstones with the soft bristles of
the brush while they are in the suds. You will need to make certain that you rinse them clear of the suds after cleaning them. After this process, use a soft cloth
or a jewelry polish cloth to pat them dry. - You can also use liquid jewelry cleaners which are sold by many department stores and jewelry stores. You can find these liquid jewelry cleaners in kit form.
Follow all the written precautions and instructions for cleaning. A home ultrasonic cleaner should be used with caution. It can be used to clean ruby, sapphire,
diamond, iolite, amethyst, citrine, garnets, iolite, chrysoberyl, and unadorned gold jewelry but it may damage gems like emerald, pink tourmaline, peridot, pearls,
coral, lapis lazuli, malachite, turquoise, and any gem that has many inclusions. When in doubt, don’t use it. - It is also a good idea to have your jewelry cleaned once a year by a professional jeweler, so he will check the security of the settings. He will also give advice for
repair of loose or bent prongs which hold your gemstones in place. This will prevent your gem from falling out of its setting and becoming lost. The jeweler will
usually give your gemstone a professional ‘shine and polish’. - Ultrasonic cleaning machines are available to clean jewelry by bombarding it with sound waves. This vibration shakes off dirt, but the vibrations can also cause
damage to the gemstone, especially brittle stones like emeralds. Any stone inclusions can be greatly enlarged by the shaking, making the gem less attractive
and valuable. For gemstones, caution is recommended when using the ultrasonic cleaners.
Storing of Colored Gemstone Jewelry
The storing of gemstone jewelry is also important as a gem can scratch another gem, as well as other jewelry pieces. Storage of gemstone jewelry should include the following precautions:
- Gemstone jewelry should be stored individually in a soft cloth
pouch to ensure that a gem should not scratch other gems or
other jewelry. - Gemstone jewelry pieces are best stored in a fabric-lined jewel
case or in a box with compartments or dividers.
Precautions for Wearing Colored
Gemstone Jewelry
You should not wear gemstone jewelry while playing sports, working on heavy equipment or relaxing in a pool or spa (especially if you are in chlorine regularly). A gemstone can be chipped by a hard blow, and even everyday activity can loosen jewelry settings.
- You should avoid a situation where your gemstones come in contact with chlorine bleach, hair spray or other chemicals because they can pit or discolor the mounting. Put on your gemstone jewelry after using makeup, perfume or cologne, and hair products.
- If you have antique or vintage jewelry, perhaps passed down to you, then consider resetting the gems into a modern style jewelry piece. Gems should be worn and enjoyed and not kept locked away in a safety deposit box.
If you will follow the above-mentioned care tips, then your gemstone jewelry will always shine and sparkle like new.
