Guide to Gemstones


A diamond is a mineral consisting of 100% Carbon. This crystallized carbon is created deep within the core of the earth more than 3 billion years ago and brought to the surface by volcanic eruption. Most of the diamonds sparkling on fingers today are more than 100 million years old! Although diamonds are associated with being a colorless stone, they are occasionally found with a strong, bright color – green, red, pink, blue, canary yellow and amber. These “fancy” colored diamonds are highly prized. Occasionally, to improve appearance, diamonds are laser-drilled, and sometimes a foreign substance is used to fill surface cavities or fractures. Diamonds may also be irradiated or heat treated to induce fancy colors.



A variety of corundum, sapphire comes in all colors except red (known as ruby), but is especially popular in deep blue. Fancy colored sapphires – including pink, green, orange and golden yellow. As part of the customary fashioning process sapphires are heated to permanently produce or intensify their color. As with all gemstones, care should be taken to protect it from scratches and sharp blows. Sapphire is found in Sri Lanka, Thailand, Cambodia, Myanmar, Australia, Nigeria, Kenya, Tanzania, China and the United States.



Ruby is known as the “Lord of the Gems” because of its rarity and beauty. Derived from the Latin word “rubber,” it simply means red. Ruby, like sapphire, is a variety of corundum and only exists as a true red in color. The finest color is a vivid, almost pure spectral red. Many believed rubies possessed an inner flame that burned eternally. As part of the customary fashioning process, virtually all rubies are heated to permanently improve their color and appearance. As with all gemstones, care should be taken to protect it from scratches and sharp blows. The finest rubies emanate from Burma, having been mined there since ancient times. Other sources include Thailand, Vietnam, Sri Lanka, Kenya, Tanzania, Cambodia, Afghanistan and India.



Emerald is one of the most highly prized of all the gems. The most prized is a pure grassy green. Emeralds are often characterized by a garden of inclusions trapped within, known as the “jardin,” because under magnification you will see all sorts of lovely patterns resembling foliage in a garden. A flawless, clear emerald is very rare and is usually found in only small sizes. Small to medium sized stones are often faceted in the “step” or emerald cut. The gem is also lovely when cut into a cabochon or dome shape. Sometimes emeralds are even carved. As part of the normal fashioning process, most emeralds are immersed in colorless oil or resin so small voids are not as noticeable. Care should be taken to protect it from scratches, sharp blows, household chemicals and extreme temperature changes. Do not use a home ultrasonic machine for emerald. Emeralds are found mainly in Colombia, Brazil, Zambia and Zimbabwe.



A pearl is the product of an oyster’s defense mechanism. When a foreign irritant is introduced either by man (cultured) or naturally, the oyster surrounds it with layers of a substance called nacre. This forms the exquisite gemstone known as a pearl. Natural pearls are extremely rare. Almost all pearls on the market today are cultured by man. Cultured pearls come in a wide range of colors. They should be relatively free of skin blemishes. The more perfectly round the shape the better. The higher the luster, or “orient,” the more valuable the specimen. The larger the cultured pearl, the greater the value. Besides the popular round shape, there are stylish mabe (large hemispherical cultured pearls), freshwater (elongated in interesting shapes and colors), and South Sea (large cultured pearls 10mm and up from the waters of Australia and Indonesia), to name a few. Pearls have been recognized as the emblem of modesty, chastity and purity. They have come to symbolize a happy marriage. Avoid household chemicals, cosmetics, hair sprays and perfumes. Don’t use ultrasonic cleaners. Wash with mild soap and water and store in a protective chamois pouch or tissue paper.



When most people think of garnet, they picture the dark red Bohemian garnet that was popular in Victorian times. You may be surprised to learn that garnets are found in every color except blue, including brilliant green tsavorite garnet, raspberry pink rhodolite garnet, and orange malaya garnet. Bright red “anthill” garnets are found in Arizona. The czars of Russia favored rare green demantoid garnets. Garnets offer enough variety in appearance to suit every taste, as well as an outstanding price range to suit every pocketbook. Garnets are durable and brilliant and will give years of pleasure. As with all gemstones, care should be taken to protect garnet from scratches, sharp blows, and extreme temperature changes. Garnets are found in the United States, Africa, Sri Lanka, Brazil and India.



Amethyst is a variety of quartz and comes in pale lilac to rich, deep purple shades. Ideally, it is a deep medium purple with rose-colored flashes that give amethyst its beauty and fire. Because of its abundance, it is readily available in all sizes and shapes. It is durable and can be worn every day. Amethyst has symbolized peace, protection and tranquility. Because royalty has always adored the color purple, amethysts abound in the ornaments of ancient Greeks and Egyptians, and in the British crown jewels. As with all gemstones, care should be taken to protect amethyst from scratches and sharp blows. It is found mainly in Brazil, Uruguay and Zambia.



The ideal color of aquamarine is a refreshing pastel sea blue. Stones with a clear blue color without green or gray are generally the most valuable. If you are looking for a big, durable gemstone, aquamarine is readily available in larger sizes and is truly dramatic when cut in rectangular or oval shapes. It is a member of the beryl family, which also includes emerald. As part of the normal finishing process, some aquamarines are heated to remove traces of green and yellow. To maintain the brilliance of this beautiful gemstone, it should be immersed in jewelry cleaner or in lukewarm soapy water and cleaned with a small bristle brush. Do not use an ultrasonic machine to clean aquamarine. As with all gemstones, care should be taken to protect it from scratches and sharp blows. Aquamarine is found mainly in Brazil, Nigeria, Zambia and Madagascar.



Peridot should be a lively lime green, without a brownish or olive cast. Peridot is the child of volcanic action. Tiny peridot crystals are sometimes combed from the black sands of Hawaii. Care should be taken to protect peridot from scratches, sharp blows, household chemicals and extreme temperature changes. Do not use a home ultrasonic machine for cleaning peridot. The peridot is abundant and is available in larger sizes. It is found in Burma and the United States. The most important source of peridot in the world is the San Carlos Apache Indian Reservation near Globe, Arizona, where it is mined by Native Americans. Large sizes are mined in Myanmar, and peridot is also found in China.



White opal has a white or light body color with flashes of many colors. Black opal has a black, dark blue, dark green or gray body color with vivid flashes of color such as red, pink and bright green. Opal has symbolized hope, innocence and purity through the ages. Care should be taken to protect opal from scratches, sharp blows, household chemicals and extreme temperature changes. To maintain the brilliance of opal, it should be wiped clean with a soft cloth. Keep from long exposure to dry heat or sunlight. Do not use a home ultrasonic machine or jewelry cleaner. Opal sources are Australia, Mexico and the United States.



Tourmaline has many color combinations in one stone, which accounts for its popularity. It is not as fragile as opal and is sometimes selected by those who prefer faceted stones. Vivid reds, hot pinks, verdant greens and blues abound in this marvelous gem variety. Earth tones as varied as a prairie sunset are readily available. Not only does Tourmaline occur in a spectacular range of colors, but it also combines those colors in a single gemstone called “bi-color” or “parti-color” Tourmaline. One color combination with a pink center and a green outer rim called “watermelon” Tourmaline is cut in thin slices similar to its namesake. Tourmalines are available in faceted or cabochon cuts and a range of sizes and shapes. They are mined in many parts of the world including Brazil, Afghanistan, East Africa and the United States.



Most people think of topaz as a transparent golden yellow gemstone. However, this gemstone can occur colorless as well as orange-yellow, red, honey-brown (dark sherry), light green, blue and pink. The name topaz is derived from the Greek word meaning “to shine” and also implies “fire.” Orange-red imperial topaz and pink colors are rare and most valuable. The lore, magic and romance of topaz goes back many thousands of years. As part of the normal fashioning process, most brownish to sherry brown topaz is heated to produce a permanent pink color. Certain types of topaz are irradiated and heated to produce shades of blue. Topaz is found mainly in Brazil, Nigeria, Sri Lanka, Pakistan and China.( see treatment and enhancements below)



Citrine is often used an alternative to topaz because it appears in many of the same colors as topaz. Unlike topaz, citrine is readily available and inexpensive even in large sizes. Citrine is in the Quartz family and is often found along side Amethyst. There is a separate classification called Ametrine, where you will see a half purple and half golden yellow stone



Colors of turquoise range from sky blue (the most desirable color) to blue green and apple green. The name means “Turkish stone,” because the trade route that brought it to Europe used to come via Turkey. The best qualities are found in northeast Iran (Persian turquoise). However, the southwestern United States is now the world leader in production. The deposits in Sinai were already worked out by 4,000 B.C. At that time the stone was used for jewelry, amulets and in the preparation of cosmetics. During the 16th century, turquoise was used as currency by the Southwest Indians. Although large quantities of beautiful turquoise that have not been color enhanced are available, today’s turquoise is commonly stabilized with plastic to improve its color and durability. Chalky varieties of turquoise are normally impregnated with oil or wax to enhance color. This color change may not be permanent. Care should be taken to protect turquoise from scratches, sharp blows, hot water and household chemicals. Do not use a home ultrasonic machine for turquoise.



Today, most gemstones are enhanced or treated. Although many of the treatments are stable, be mindful that some are not.


Common diamond treatments today are clarity enhancement and laser drilling. Clarity enhancement is the process in which imperfections are filled with a glass-like substance to improve the appearance of the diamond. Extreme heat, such as that from a jeweler’s torch, or specifically formulated chemicals can remove the filler. In laser drilling a laser is used to reach dark inclusions within the diamond. Often a bleaching agent is added to make the inclusion less visible. Laser drilling is stable.

Rubies and Sapphires

Rubies and sapphires are usually heated to improve their color and clarity. Sometimes, a glass-like substance is used to fill the cavities, and improve the appearance of the gemstone.


Emeralds are a naturally included gemstone, and have been oiled for hundreds of years. Today, more sophisticated resins and hardeners are used to enhance the clarity of emeralds. These treatments are not permanent, so this gemstone should be treated with extreme care.


Tanzanite brings to the minds of most jewelry lovers a bright blue or violet color. However, just about all tanzanite comes out of the mines an orange-brown color. It is then heated to produce the spectacular violet-blue we are familiar with. This is a permanent process.

Amethyst and Citrine

Amethyst and Citrine are members of the quartz family. If amethyst is heated to a certain temperature, it turns into the bright yellow or orange color of citrine. This is a permanent and stable enhancement.

Blue Topaz

Blue Topaz is rarely produced in the beautiful shades we are familiar with. After the topaz is mined, it is irradiated to brown and then heated to blue. This is a permanent process.

Information provided by: Jewelers of America: JA, Gemological Institute of America: GIA, and the Jewelers Vigilance Committee: JVC