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FAMILY : Quartz
ORIGIN: The finest amethysts come from Brazil and Madagascar.
APPEARANCE: The typical color of amethyst is a rich, violet-purple, often distributed in patches or bands. It can also be quite pale, but is generally the same basic color without any overtones.
PHYSICAL PROPERTIES: Amethyst has a hardness of 7. The density is 2.65 g/cm^3 and refractive indices are nw 1 544, ne 1.553 are very constant because of the invariability of the quartz's chemical composition.
DISTINCTIVE FEATURES: The distribution of color, in striking patches and bands, is characteristic. When the stones contain inclusions, a series of discontinues, wavy, parallel lines, visible with a lens, indicates that they are certainly natural Amethyst.
VALUE: A few centuries ago, a deep color amethyst was highly prized. It value fell greatly with the discovery of the large Brazilian and Uruguayan deposits at the end of the 19th century. Now relegated to the status of a secondary gem, its value is quite low.
SIMULANTS AND SYNTHETICS: Amethyst was much imitated by colored glass in the past, when it was more costly. Nowadays, despite the limited value of the natural stone, fair quantities of synthetic Amethyst are produced, using the knowledge acquired in the production of synthetic quartz for technological purposes. The cost of the synthetic product is not much less than that of the natural gemstone.
APPEARANCE: The most valuable color is a rich, sky blue; but because the stone is plethoric, even the blue stones have a green or greenish-blue tinge in one direction. Quite large stones, ranging from several carats to more than ten or a few tens of carats, are relatively common. Many are virtually free of inclusions. The luster is vitreous and not exceptional. The most common cut is the emerald type, although mixed oval or pear-shaped cuts are not infrequent.
HARDNESS: It has a hardness of 7.5 to 8, but is fairly brittle, and may show ill-defined cleavage paralleled to the basal plane.
DISTINCTIVE FEATURES: The color of this stone, combined with its particular type of pleochroism and vitreous luster, distinguishes it fairly easily from blue topaz and light-blue synthetic spinel.
VALUE: Rich blue stones several carats in weight are among the most valuable of secondary gems. Pale of green stones are much less valuable.
SIMULANTS AND SYNTHETICS: Aquamarine is imitated by blue glass, which faithfully reproduces the color, if not the pleochroism, but it is most often imitated by blue synthetic spinel, of slightly different color, with a superior luster and no pleochroism.
APPEARANCE: The color of Citrine varies from pure yellow to dull yellow, honey, or brownish yellow. As with Amethyst, the color is broken up into patches or bands, although due to its depth or hue, the zoning is less obvious. It has good luster (like amethyst) and is generally very clear and virtually free of inclusions.
DISTINCTIVE FEATURES: Color zoning when present may be an aid to recognition. The density of citrine is the lowest for stones of this color. Citrine can only be distinguished from the numerous other yellow stones by an examination of the physical properties.
VALUE: Quite low for paler pieces, finer and deeper colored gems bring higher prices.
SIMULANTS AND SYNTHETICS: It is not imitated; but despite its low value, it is synthesized, like amethyst, on a large scale. The cost of the synthetic version is equal to or only slightly lower that that of the natural gemstone. Amethyst, when heated, assumes the yellow color of citrine.
ORIGIN: Mostly in Colombia and Brazil and now deposits have been found in East Africa.
HARDNESS: It has a hardness of 7.5 to 8, but is fairly brittle, and may show ill-defined cleavage paralled to the basal plane
APPEARANCE: The typical color is a beautiful, distinctive hue known, in fact, as emerald green and is due to traces of chromium in the crystal structure. But emerald can be light or dark green, bright green or leaf green. The vitreous luster is not outstanding, and is strongest in medium-light stones with few inclusions. All emerald contains inclusions, although in the best quality stones, these are very faint and not visible to the naked eye.
VALUE: Stones of fine color, weighing more than 2 carats, are among the most highly valued gemstones, and their price may equal or exceed that of diamonds. Less ideally colored varieties - too dark or too pale - are worth quite a lot less; and if they are slightly dirty as well, the value is reduced even further.
SIMULANTS AND SYNTHETICS: Doublets have been used as imitations, with a lower portion of green glass and a top portion of garnet, or triplets, with a layer of colored cement sandwiched between two layers of colorless beryl, synthetic spinel, or quartz.Synthetic emeralds have likewise been widely produced over the last few decades. Generally of good color, these are mainly distinguished from the natural variety by their inclusions and other growth features.
ORIGIN: India and Sri Lanka
APPEARANCE: The color is red, but often a deep, violet-red. It has brilliant luster, but its transparency is frequently marred, even in very clear stones, by excessive depth of color.
DISTINCTIVE FEATURES: The deep, almost violet-red is fairly typical, and had given rise to the expression "garnet red." It is not enlivened, as are dark rubies, even by strong light, and its single refraction and lack of visible pleochroism should normally distinguish it from similarly colored rubellite.
VALUE: This depends on brightness of color and freedom from cracks and inclusions, but is very affordable.
SIMULANTS AND SYNTHETICS: Almandine has been imitated by glass, which can look very similar. It has apparently been produced synthetically, but not on a commercial basis.
ORIGIN: India, Sri Lanka
APPEARANCE: Moonstone generally has an almost transparent ground, which is practically colorless, pale gray or tinged with yellow, with a whitish to silvery white or blue shimmer. It is normally cut into cabochons or curved pieces for threading into necklaces, etc.
DISTINCTIVE FEATURES: Adularescence (a slight turbidity with a mobile reflection) is in itself distinctive. Another feldspar, albite, can look identical and is also called moonstone.
VALUE: Fairly low, but the type with a blue sheen is quite highly priced.
SIMULANTS AND SYNTHETICS: It has been imitated by milky synthetic Spinel. It has not been manufactured synthetically.
ORIGIN: Australia, Mexico
APPEARANCE: Opal may have a whitish to light gray, pale green, sky blue, smoke gray, black, yellowish to orange or reddish background color. It is more often translucent and milky, with an appearance, which is so characteristic, it is described as opalescent. Opals can be fully or largely transparent; such stones are usually orange-yellow to red in color. The most highly prized varieties display internal iridescence due to light defraction by the network of tiny spheres of which they are composed. The range or color apparently depends on the size of the spheres or rather the distance between the rows.
DISTINCTIVE FEATURES: White opal is unmistakably more immediately recognizable than any other gem. There is, of course, the problem of distinguishing it from black opal, given the wide range of gradation form one to the other. It is called black when the background color is mid-gray, smoke gray, blue or black; otherwise it is called white.
VALUE: The best quality gems fetch very high prices, exceeded only by the four principal gemstones (diamond, emerald, ruby, sapphire,) imperial jade, alexandrite, and black opal. Many specimens, which are pleasing in appearance, are quite modestly priced, while other specimens with weak, barely visible iridescence are fairly cheap.
SIMULANTS AND SYNTHETICS: It was long considered impossible to imitate opal. White opal has been manufactured synthetically by a French company for nearly a decade; the appearance of its iridecencent patches is fairly distinctive, but an expert can nonetheless only distinguish it.
ORIGIN: United States (Arizona), Burma, Brazil and Pakistan.
HARDNESS: 6.5 - 7.0
APPEARANCE: Typically Olive Green, peridot can be a strong almost bottle green or yellowish green. The stones are usually transparent with few inclusions, and are given all types of mixed cuts, oval, round, pear shaped, plus rectangular and square cuts.
DISTINCTIVE FEATURES: The particular color and luster are highly characteristic, although some tourmalines and zircons may look much the same. A quick way of distinguishing them is by testing the density. The particular color and luster are highly characteristic, although some tourmalines and zircons may look much the same. A quick way of distinguishing them is by testing the density.
VALUE: Much appreciated in the past, Peridot is the victim of changing fashion and is far less highly priced today. Even exceptionally fine, large stones are very affordable today.
SIMULANTS AND SYNTHETICS: Appropriately colored glass, synthetic corundum and synthetic spinel have imitated peridot. It has also been synthesized experimentally, but its abundance has discouraged such attempts.
ORIGIN: Burma and Thailand
HARDNESS : 9.0, the highest in the mineral world after diamonds.
APPEARANCE: The most valuable variety of corundum is ruby. The color varies from fiery vermilion to violet red, but because rubies are pleochroic, i.e. display more than one color due to the different absorption of light in different directions, different colors are found in the same stone. If the color is too pale, they are no longer called rubies, but pink sapphires. But it is hard to establish precise limits, as all the intermediate shades are possible. The brightest red and thus the most valuable rubies (usually from Burma) often have areas full of inclusions in the form of minute rutile needles (or straws), which interfere with light, producing a distinctive silky sheen, known, in fact, as silk. Rubies are usually given a mixed cut, which is generally oval, but can be round or, more rarely, other shapes.
DISTINCTIVE FEATURES: Rubies can often be distinguished by their immediately visible characteristics: a fairly obvious pleochroism, a distinct brightening of color in strong light, the silk effect (when present), and a considerable luster.
VALUE: The highest quality, best colored and most transparent stones (usually from Burma), weighing for example, 3 to 5 carats, can be as valuable as diamonds, or even more so. The price falls considerable for stones of less than a carat, which are too dark in color, and have inclusions clearly visible to the naked eye.
SIMULANTS AND SYNTHETICS: Synthetic Ruby has been produced since the beginning of the 20th century and was the first synthetic gemstone to be manufactured on an industrial scale. More recently, doublet-imitating rubies have also been produced in the orient. The top part of these doublets consists of poorly colored natural corundum, with obvious, typical inclusions; and the lower part is synthetic ruby held to the corundum by transparent cement.
ORIGIN: Sri-Lanka, Thailand, and Australia
HARDNESS: 9.0, the highest in the mineral world after diamonds.
APPEARANCE: Sapphire is a variety of corundum. Sapphires can be blue, yellow, purple, green, pink, and any color other than red, which is known as ruby.
DISTINCTIVE FEATURES: Like other types of corundum, sapphire always has good luster.
VALUE: The finest stones, weighing at least several carats, are almost as valuable as diamonds and rubies and are therefore very highly priced. But when the color is too dark, blackish or greenish blue or a bit too pale, the value falls sharply. Inclusions obvious to the naked eye also lower the price.
SIMULANTS AND SYNTHETICS: Sapphire has been imitated by cobalt blue glass, but particularly by doublets that have been produced consisting of a top portion of a light green or yellow-green natural corundum with visible inclusions and a lower portion of synthetic sapphire held together by transparent cement.
APPEARANCE: This gem has a characteristic blue color, usually with a violet tinge. In lighter-colored specimens, it is almost lavender. The stones have few inclusions. It is normally given a round or oval, mixed cut, but the step cut is also used.
DISTINCTIVE FEATURES: The particular color, combined with the type of pleochroism described and moderate luster, make it fairly easy to distinguish. It is sometimes confused with sapphire, but compared with this, it is visibly less lustrous and much less hard. It also had different pleochroisn and different refractive indices.
VALUE: Given its attractive color, its rarity, the value of Tanzanite is quite high. Although due to increased availability, these stones have become more affordable to the general public.
SIMULANTS AND SYNTHETICS: Only recently has this stone been imitated synthetically, details of which are not available.
APPEARANCE: This is the variety of topaz most readily available in the market today. Often pale, it can be bright or very rarely an intense blue. Gemstones of several carats of even several tens of carats in weight are common. Further more, they are usually wholly or almost free of inclusions.
DISTINCTIVE FEATURES: There is, at first sight, some resemblance to aquamarine; but close observation will distinguish the two, as aquamarine always displays a very attractive pleochroism from blue to greenish blue or even bluish green.
VALUE: Less than that of aquamarine. The ready availability of blue topaz in the market, even in pieces of considerable size is probably responsible for this.
SIMULANTS AND SYNTHETICS: although blue topaz has not been manufactured synthetically on a commercial scale, a completely natural looking coloration has been produced during recent years in colorless topaz by means of irradiation. This practice, regarded as legitimate in the trade is becoming increasingly wide spread and is one of the reasons for the presents abundance of Blue Topaz.
APPEARANCE: Green colored Tourmaline comes in a wide range of different shades, so, at first sight, many green tourmalines may look similar to other gems. Shades may include the yellowish-green of some olivine's, or the stronger, deeper green of others; a lightish pink box green, like some zircons, is also possible as a stronger version of this color, like some African Emeralds. Mid to light colored specimens have good luster. Darker stones often look a bit opaque.
DISTINCTIVE FEATURES: The more definite or darker shades are characteristic. Loss of transparency along the stone, particularly in gems that are cut retangularly is peculiar to tourmaline.
VALUE: Only the lively mid colored stones are valuable. When the color is an uncharacteristic pale green, or the most typical dark or olive green, they are worth much less.
SIMULANTS AND SYNTHETICS: It is neither imitated nor produced synthetically.
|2nd||Garnet (all colors)||21st||Iolite|
|3rd||Pearls||22nd||Spinel (all colors)|
|5th||Sapphire (all colors)||24th||Tanzanite|
|8th||Tourmaline (all colors)||30th||Pearl Jubilee|
|9th||Lapis Lazuli||35th||Emerald or Coral|
|10th||Diamond Jewelry||39th||Cat's Eye|
|12th||Jade or Agate||45th||Sapphire or Alexandrite|
|13th||Citrine or Moonstone||50th||Golden Jubilee|
|14th||Opal or Moss Agate||52nd||Star Ruby|
|15th||Ruby||55th||Alexandrite or >Emerald|
|16th||Peridot or Topaz (all colors)||60th||Diamond Jubilee|
|January||Garnet, Rhodolite||July||Ruby, Carnelian|
|June||Alexandrite, Pearl, Moonstone||December||Blue Zircon, Turquoise, Lapis Lazuli|
|Gems of Spring||Gems of Autumn||Gems of Summer||Gems of Winter|
|Scorpio||Dark Red||Red Garnet||Steel|
|Sagittarius||Deep Blue||Blue Sapphire||Tin|
|Sunday||Topaz or Diamond|
|Tuesday||Ruby or Emerald|
|Thursday||Sapphire or Carnelian|
Mental clarity: Amber, Fluorite, Lapis Lazuli, Moonstone, Silver Topaz, Smoky Quartz.
Productivity: Agate, Garnet, Opal, Rhodolite.
Building self esteem: Aventurine, Carnelian, Diamond, Emerald, Garnet, Spinel.
Feelings of happiness: Agate, Amethyst , Calcite, Diamond, Jade, Tsavorite.
Calmness and balance: Amethyst , Ametrine, Aquamarine, Citrine , Coral, Diamond, Jade, Malachite, Pink Tourmaline, Tanzanite, Zircon.
Feelings of strength and confidence: Agate, Amber, Aquamarine, Carnelian, Diamond, Garnet, Iolite, Malachite, Onyx, Opal, Ruby, Sapphire, Topaz (blue).
Wisdom: Coral, Jade, Pearl, Sodalite.
Luck: Alexandrite, Amber, Aventurine, Opal, Pearl, Turquoise.
Love and friendship: Alexandrite, Amber, Amethyst , Emerald, Moonstone, Pink Tourmaline, Sapphire, Topaz.
Wealth: Aventurine, Calcite, Emerald, Jade, Opal, Pearl, Peridot, Ruby,
Sapphire, Topaz, Tourmaline.
|Venus||Emerald, Jade||Neptune||Opal, Amethyst|
|Mars||Ruby, Garnet, Bloodstone||Moon||Pearl, Moonstone|
|Jupiter||Amethyst , Sapphire||Sun||Topaz, Ruby|
|Saturn||Sapphire, Onyx, Obsidian|
PHYSICAL CHARACTERISTICS OF