Jewelry: Popular Gemstones – Agate to Emerald
AGATA – Agate consists of silicon dioxide that settled in ancient times to form beautiful flowing bands of different textures and colors. There are always many layers and bands of different materials in all kinds of designs and colors, in quartz, chalcedony, jasper or iron oxides, making agate one of the most fascinating gemstones for the lapidary. Agates of all kinds have been popular in talismans throughout the centuries. Beautiful specimens of concentric rings are found in Winona, Minnesota. Heating agate artificially produces even more spectacular agates. There are many different types of agates: moss or seaweed agates, depleted coral, crazy lace agate, feather agate or scenic agate, arboreal agates, onyx agate, eye agate, and rainbow or rainbow agate with their many colors.
AMBER – The name is Arabic but it has come to us from French and in Greek it means ‘electricity’. Pliny stated that amber is the sap of certain trees. It is now confirmed to be the fossil resin of an extinct species of pine from the Tertiary period. . Often it preserves within itself plant structures and insects. In prehistoric times it was used as a talismanic amulet against diseases and was also burned as incense. It has a peculiar electrical property discovered by Thales, one of the 7 sages of Greece, when it is subjected to friction on a natural wool material to demonstrate an electromagnetic power. Amber is found in colors ranging from green to gold and orange, to brown, and even red. It is transparent or opaque in nature with any cloudy appearance caused by trapped bubbles. Amber was also used as an essence or aroma and is still used as an ingredient in modern perfumes. Amber has a wide distribution in Europe, Sicily and the Adriatic, Australasia, America and Russia, Siberia, Greenland, the United States, Mexico, Burma and Romania. Occasionally it washes up on the beaches.
AMETHYST – Western or True Amethyst is a form of quartz. or colored rock crystal consisting of silica. Oriental amethyst is alumina. Others are violone, a lithium aluminum silicate. Contains iron in quartz. The deeper the color, the more valuable, due to the presence of manganese oxide. The oriental amethyst or violet sapphire is a form of corundum similar to sapphire and ruby. A beautiful specimen is a violet gem weighing 48 carats in the Allison Gem Collection, Australia The best examples come from Siberia, Ceylon, Brazil and Persia, but a large one found in an amethyst cave in Brazil is a huge crystal measuring 33 ‘ by 6 ‘x 3’, the largest ever found.
AQUAMARINE – This gemstone is a transparent pale aqua blue beryl with iron giving it a green / blue tint, ranging from pale green to deep sea green. It is relatively inexpensive and is mined in India, Siberia and Brazil, the most abundant source of aquamarine. This bluish-green stone is heated to produce the blue color so popular in modern jewelry. A magnificent 46 carat example is found in Allison’s collection of Australian gemstones.
BERYL: Beryl is used as a copper alloy and also in the construction of the atomic bomb. Beryl and aquamarine differ only in color: beryl is bright blue to white, and aquamarine is sea green to dark green. The best known is the dark green form of beryl, the precious emerald. Yellow beryl is heliodor and pink beryl is morganite and there is also an extremely rare red beryl. Beryl is known for its huge crystals. Madagascar produced a single crystal that weighed almost 40 tons, far exceeding the monstrous 18-27 feet previously obtained from New England.
BLOODSTONE – Bloodstone is opaque and always cut like a cabochon or stone without facets. It is a variety of green Jasper with many blood red spots in its composition. These are made up of iron oxide with which it is impregnated. Ancient Egyptians valued bloodstone amulets. It was once very popular for cutting stamps and cameos. Found in India, Siberia, and Russia. The Chinese believe that it produces better results when it is set in gold.
CARNELIANA (Carnelian): This is a translucent orange-red chalcedony sometimes found in yellowish and white hues, often with two combined. When exposed to the sun, the tones become brighter but not under artificial light. It is capable of high polishing, which is why it was considered the best stone to use as a stamp, according to Pliny. The transparent red type of carnelian is known as Sard and comes from Arabia, India, New Zealand, Europe, Mesopotamia, Suriname, and Siberia. Many ancient Etruscan and Egyptian scarabaei carved on this stone have been found. Buddhism includes this in the 7 sacred stones: Tibetans call it A-yu and as a talisman it has hidden properties.
CORAL – Coral is formed from calcium carbonate in the skeletons of colonies of soft-bodied mollusks in tropical waters. Its color ranges from rare black to pink to reddish orange, the classic “coral” of fashion. It is also in blue. The ancient Romans and Greeks used it in ornamentation. Red, pink, white and blue corals are made of calcium carbonate, but black and gold corals are made up of the horny substance conchiolin. In all corals, the skeletal structure is visible as a delicate strip of stained veins. Red and pink corals of the Mediterranean. They were popular for centuries and were often used on rosaries. There was extensive trade across Europe to Arabia and to India, where coral was also used for medicinal purposes. The black and gold corals caught in Hawaii, Australia and the West Indies are more recent discoveries.
CRYSTAL – Rock crystal or ice water has always been considered a pure stone and was once used as a fortune telling stone and in modern divination when Gypsies keep alive the tradition of using a crystal ball, a custom that is says it started in Persia. The stone is traditionally associated with mystical properties and is linked to the moon. It is one of the 7 sacred substances of Buddhism. Its crystal has 6 sides and is rarely found in large pieces, but the largest quartz crystal ever found was in Brazil, it was over 5 meters long and weighed over 48 tons! Synthetic rock crystal is manufactured in Japan for industry and also for jewelry.
DIAMOND – Diamond: the most beautiful and popular gemstone consists of pure carbon, the blackest substance, which crystallizes in the cubic system at enormous pressures and high temperatures, sometimes from a depth of 150 km in the earth. Aside from the unique flashes of light and color from its faceted stone, the diamond has special properties and is the hardest of all stones. The best quality stones are colored and transparent with a slightly blue tint, but pink and tinted diamonds are also becoming popular. Diamonds are said to have been found for the first time in India over 2000 years ago. Previously in that country diamonds were known but they were never cut because it was believed that they had magical properties, they were destroyed by cutting. Cutting in Europe began after 1300 AD. Lasers are now used to cut diamonds, but the only mineral capable of cutting a diamond is a diamond. The main world producers now are Northern Australia, which supplies 1/4 of the world’s needs, especially for industrial purposes and also colored “champagne diamonds” and in the South African Kimberley region.
Emerald – Emeralds are green forms of Beryl and the best are found in Bolivia, Brazil, and Colombia. Also India and Pakistan, but the best are said to come from Colombia near Chivor, where they are found in veins within dark shales and limestone. The Ural Mountains, rich in emeralds, preserve the world market. Egypt’s emerald mines are over 4,000 years old. Pliny tells of a colossal 13 1/2 foot tall emerald statue of Serapis in the ancient Egyptian labyrinth. He was called the “king” of the green stones with an extremely high value due to his rarity and the fact that he had seldom carved out of flawless gemstones. The largest emerald ever discovered was 11,000 carats found in an uncut state in South Africa. The largest quality carved stone was 1,347 carats, but it had obvious flaws. The largest known perfect stone was that of the Tsar of Russia: 30 carats. The Crown of the Andes made in 1593-99 in South America had 453 emeralds, the largest being 45 carats. However, synthetic emeralds in modern times have plausible inclusions, so testing must be done carefully to determine the quality of the stone.