All About Gemstones

Agate

• Hardness 7
• A type of chalcedony; a crypto-crystalline quartz.
• The name comes from an ancient, now untraceable Sicilian river, Achates.
• Worn by a farmer on the upper arm to insure a good harvest
• Placed on right horn of oxen to protect them.
• Red - protection from spiders and scorpions.
• Green - relief from eye trouble.
• Green with stripes - A woman who drinks water in which such a ring has been washed will never be sterile.
• Grey - worn on the neck to prevent a stiff neck.
• Moss agate - also called dendritic (Greek, "dendron," tree)

Alexandrite

• Hardness 8.5
• This natural stone is a type of chrysoberyl that shows a range of transparent colors, from blue in daylight to reddish-yellow in artificial light.
• More widely available is a synthetic stone, actually a treated corundum, H9.
• The stone was named for Czar Alexander 11 who, according to legend, came of legal age on the day the stone was discovered. 

Amber

• Hardness 2 to 2.5
• This is not a stone but the naturally hardened resin of pinus suceinifera, the amber pine.
• Transparent amber is 120-180 million years old. Opaque amber, called copal, is 60 million years old.
• The name comes from the Arabic anbar. The Greeks called it elektrum from the Phoenician word for sun or golden. Because amber will hold a charge this gave us our word electric.
• To test a sample, brush it with methyl alcohol or ethylacetate. Nonfossil resin such as plastic will dissolve.
• Another test is to set into brine: real amber will float but artificial will sink.
• Amber can also be tested by touching with a hot needle. The smoke thus caused will either smell like a pine woods or a plastics factory.
• Some amber contains thousands of tiny air bubbles. This is called bone amber and can be cleared by heating in oil.
• Magical Uses
• Amber dust mixed with honey or water was  used to treat ears, eyes, stomach, liver, and kidneys.
• The smell of burning amber helps a woman in labor.
• Holding an amber ball will keep one cool on the a hot day. It was used to treat fever victims.
• Amber beads preserve the wearer against rheumatism, toothache, rickets and jaundice. 
• Amber will dissolve in solvents like acetone or nail polish remover. It will be worn down by mechanical buffing with compounds like tripoli. 

Amethyst

• Hardness 7
• A form of quartz.  The top grade is a deep purple and has no flaws or inclusions.
• From the Greek for not drunken. The gem was believed to protect from the effects of wine, especially if held under the tongue while drinking.
• When heated to 550-560C amethysts turn dark yellow or reddish-brown and are called citrines. They are more richly colored and more expensive than natural citrines.
• The color can fade if the stone is left in strong sunlight for a long time.
• Placed under the pillow, amethysts insure pleasant dreams, improve memory, and provide immunity from poison.
• Some people believe that a wearer of this stone will become gentle and amiable.

Andesine

• Hardness 6-6.5
• A form of labradorite.  The top grade has a distinctive ingot-hot orange-red like molten metal. A glowing ember red.
• It is relatively soft therefore easily scratched, lost, or broken.
• Found in Western China.

Aquamarine

• Hardness 7.5 to 8
• The name comes from the Latin, "beryllus aquamarinus," beryl resembling seawater.
• It is traditionally a sailor's talisman.
• This gem increased in popularity around 1920 when heat treatment was developed to turn pale stones into deeper blue shades.

Aventurine

• Hardness 7
• A fine-grained quartz with many flake inclusions, occuring in many colors, mainly green, brown, and gray.
• The ubiquitous sparkle of this stone is called aventureseence.

Beryl

• Hardness 7.5 to 8
• This stone occurs in a wide color range including pink, orange, yellow, green, blue-green and blue.
• It is also found colorless (called goshenite). This resembles rock crystal and was used  for lenses and crystal balls.                     
• Pink beryl is known as morganite, after the banker and gem collector J.P. Morgan.
• Beryls can show some chatoyancy when cut as cabochons.
• This stone is said to protect the wearer from helplessness caused by fascination. It was also used to treat diseases of the eye, jaundice and liver disease.

Carnelian

• Hardness 6.5 to 7
• A red chalcedony, its color being due to the presence of iron.
• The opaque variety is called sard. When in brown and white layers it is called sardonyx.
• Carnelian was said to stop nosebleeds and to prevent blood from rising to the head.
• It is a strong protection from the evil eye.

Chalcedony

• Hardness 6.5 to 7
• Pronounced kal-SED-ne.
• Cryptocrystalline quartz; that is, quartz with very tiny crystals. Carnelian, onyx, agates and chrysoprase are all kinds of chalcedony.                                       
• In the world of jewelry the word refers to a solid color, translucent, light blue stone. These may be made by dying agates but the naturally occurring variety is more desirable.

Chiastolite

• This is an opaque form of andalusite that grows in cigar-shaped crystals. When sliced, these show a light-colored cross or shamrock against a dark green background.
• Found near the Shrine of St. James in Santiago de Compostella in Spain where religious power is often attributed to the stone.

Chrysoberyl

• Hardness 8.5
• Pronounced KRIS-o-ber-l.
• This stone occurs in both a transparent and a cloudy variety and can be yellow, green or brown. Clear stones are usually faceted while the cloudy are cut as cabochons.             
• Chrysoberyl has one of the most attractive cat's eyes of all stones. This occurs as a bright silvery line that travels across the curved surface of a polished gem as it is moved. The effect is called chatoyancy from the French word for cat, chat.

Chrysocolla

• Hardness 5 to 6
• A hydrous silicate formed by the decomposition of copper ore near the surface.
• From the Greek, chrysos, gold and kolla, glue. In ancient usage the term included malachite. Both were used as a flux for soldering and fusing gold.            
• Occurs in variable shades of blue and green and can resemble turquoise.         
• Chrysocolla from the site of King Solomon's Mines in Eilat, Israel is called eilat (elat) stone.
• Because this is a copper-bearing ore it will be damaged by pickles, like Sparex, which attack copper oxides.

Chrysoprase

• Hardness 6.5 to 7
• From the Greek words for "gold" and "leek," referring to its golden-green color, which is caused by nickel salts.            
• A light green translucent chalcedony, the most valuable of the chalcedony family. 

Citrine

• Hardness 7
• This yellow quartz can be found naturally or may be made by heating amethyst (purple quartz) to around 550C (1050F). Treated citrines have a deeper color and are more expensive than the natural.       
• Yellow-brown variety is called cairngorn after their place of origin in Scotland.
• Dark reddish-brown quartz is called "sang de boeuf" (French for ox blood).

Coral

• Hardness 3.5
• This is not a stone in the usual sense, but a rock-like material formed from the underwater deposit of many tiny skeletons of invertebrate animals.                         
• From the Greek korallion, originally derived from the word for pebble.
• Coral can occur in many shades of reddish-pink, white, and black which is called akabar.
• Coral was thought to stop bleeding, guard against poison, and protect dogs from rabies.
• This is a soft material and should be treated gently. It will not tolerate harsh cleansers, abrasion or heat.

Corundum

• Hardness 9
• Until the Middle Ages, corundum was called hyacinth and thought to exist only as a blue stone. When it was discovered that other colors of corundum existed, the name of sapphire was used for the blue variety.        
• Corundums of other colors are usually identified by a color name, such as yellow sapphire, green sapphire, etc. except for red corundum which is called ruby.
• Corundum occurs in yellow, green, reddish-yellow, pink, mauve, brown and black.

Danburite

• Hardness 7
• A colorless form of calcium boro-silicate.
• Named after it's discovery location - Danbury, Connecticut in 1880.
• Can be a substitute for diamond where a natural, low-cost stone is desired over a CZ.
• Found mostly in Mexico, but also in Madagascar & Burma.

Diamond

• Hardness 10
• From the Greek "adamas," unbreakable, indomitable.
• Diamonds were believed to render all poisons harmless and to drive away madness, night spirits and evil dreams.

Emerald

• Hardness 7.5 to 8
• A bright green beryl, very valuable if free of inclusions and of strong color.
• Emeralds are notoriously brittle and need great care in setting. For this reason a thick girdle on a faceted stone is preferred.            
• Do not clean emeralds in an ultrasonic machine. The solution may penetrate the stone and cause it to shatter.
• Inclusions are called the "jardin" (French, garden) of the stone.
• Linked to fertility and the Earth Goddess, it is a birthstone of spring.
• Sacred to the Goddess Venus, worn by women to ease childbirth.
• Said to stifle an epileptic fit.

Fluorite

• Hardness 4
• A form of calcium fluoride, available in a spectrum of colors but desired for its ravishing green, reminiscent of emerald.
• Its softness requires that it be used in pendants much more than rings.
• Readable available in large sizes.
• It's carvable, can be used in bowls and vases
• Found in many locations, green from New Hampshire, intense purple-blue from Pakistan, etc.

• Hardness 6.5 to 7.5
• From the Latin "granum," grain or pip, which in turn came from the Phoenician word for pomegranate, 'punica granatum."              
• When on the body, garnets are said to prevent skin diseases.
• Garnet assures the wearer of love, faithfulness and safety from wounds.
• When danger approaches, the stone loses its brilliance. 
• For obvious reasons red garnets have been associated with blood. As recently as 1892 native soldiers in the Kashmir fought the British with bullets made of garnet, in the belief that these would find their way magically to their targets.                               
• Garnets will protect the wearer from evil and from terrifying dreams. 
• Types of garnets:
  • Pyrope - A deep red color. Its name in The Greek means "fiery eye."
  • Almadine - Dark red with a tinge of mauve. Purple variety is called rhodolite.
  • Spessartite - Red-orange or orange-brown. Shows internal wavy veil of fluid contained in the stone. Rare and expensive.
  • Grossular (Grossularite) - A speckled green stone resembling jade. Hessonite is a sub-species.
  • Uvarovite - Rare, intensely green stone.
  • Andradite - This contains iron. It is rarely cut.

Hematite

• Hardness 5.5 to 6.5
• A lustrous black stone often cut with facets or carved with a warrior's head. 
• Though the stone is black, it will leave a red streak when scratched along a rough surface. The stone appears to "bleed" and so takes its name from the the Latin word for blood, "haima."
• Hematite (also spelled "haematite") is the world's most important iron ore.
• Powdered hematite is known as red ochre when used as a pigment and as crocus when used as a polishing compound or abrasive.
• Hematite can form naturally as a cluster of thin plates and in this configuration is known as an alpine rose or iron rose.

Ivory

• Hardness 2.5
• Ivory comes from the tusks of elephants and is becoming increasingly rare as the elephant approaches extinction. In many parts of the world it is illegal to use ivory.   
• Other similar materials should be identified with an adjective, as whale ivory. True ivory is made up of many translucent layers and has a soft sheen caused by the partial penetration of light.
• Ivory can be identified by a characteristic grain pattern. This becomes more obvious with age.

Jade

• Hardness 6 to 6
• The term jade refers to two distinct minerals not differentiated until 1863. These are properly called jadeite and nephrite.          
• Spanish conquistadors found many objects of carved jade and, believing it to ease kidney pains, called it "piedra de ijada" (loin stone). European doctors called it "palis nephriticus" from the Greek "nephros," kidney.
• Because of its waxy lustre, the Chinese called it wet stone and believed it could slake thirst.
• Jade occurs in white (mutton fat), yellow, lavender, earthy brown and black as well as the familiar greens.
• Jade can be confused with californite, grossularite, sausserite, pectolite, chrysoprase and aventurine.
• This stone was believed to protect from lightning, to aid in battle, to bring rain, to drive away beasts and evil spirits and to aid in childbirth.

Jasper

• Hardness 6.5 to 7
• From the Hebrew yashpeh and Assyrian yashpu referred to in Cuneiform writings of 1500 BC. Originally the word meant any green stone.                                      
• Jasper occurs in many colors and patterns, including stripes and pictures. These are really fossilized algae made when decomposed organic matter was replaced by silicon oxide (i.e. jasper).                   
• Green chalcedony with flecks of red jasper is called bloodstone or heliotrope.
• In ancient Egypt, red jasper was associated with the blood of Isis.
• Green jasper was associated with St. Peter by the early Christians.
• Said to drive away night spirits, staunch bleeding, and help during pregnancy.
• Green jasper was used in rainmaking.

Jet

• Hardness 3 to 4
• A dense black coal found in many places around the world. Especially popular in Britain under the reign of Queen Victoria, when most jet came from the town of Whitby. 
• Jet nullifies spells and charms.                                              
• Burnt and powdered jet is said to drive away snakes and reptiles and to heal toothaches and headaches.
• Traditionally Irish housewives burned jet during their husband's absence to insure his safety.

Kornerupine

• Hardness 6 1/2
• Pronounced korner-roo-peen. 
• Pleochroic, known for its color blends, blue-green & purple.  (Not a color-change gem like alexandrite, but a color-shift gem like andalusite.)                                  
• Rarely seen in stones over 1 1/4 carat.
• Discovered in Sri Lanka in the 1960's, but as a mostly sage-green stone.
• Found mostly in Tanzania as a better color identity.

Labradorite

• Hardness 6 to 6.5
• This is a blue iridescent feldspar found on the coast of Labrador.
• A similar gem mined in Finland shows a wider range of colors and is called spectrolite.
• Black moonstone is usually labradorite from Madagascar.

Lapis Lazuli

• Hardness 5 to 6
• From the Latin "lapis," stone and Arabic "lazuli," blue. 
• Known for its deep blue color, sometimes found with flecks of gold-colored pyrite or whitish-gray mottlings of calcite.                  
• Lapis is still being mined in Afghanistan at the oldest mine in the world. When mining began 6000 years ago, the country was called Babylon.                                    
• Lapis was sent to Egypt as tribute. There it was carved to make cylinder seals and ground to a powder for eye makeup.                     
• In Ur, kings sharpened their swords on lapis in the belief that it would make weapons invincible.
• Sumerians believed that a wearer carried the presence of God with him.
• In ancient Egypt, the stone was symbolic of truth (Ma) and was worn by the chief justice.
• In the Middle Ages, painters mixed oil with powdered lapis to make the color aquamarine.
• The gem is believed to ease eye troubles, asthma, to induce sleep and relieve anxiety.

Malachite

• Hardness 5 to 6
• A copper ore made up of deep and pale green stripes or concentric circles. Because it is formed in thin layers, large pieces are somewhat rare.
• Malachite powder was used by the ancients as eye makeup.
• It was commonly held to ease labor, protect infants and children, and soothe their pain when they were cutting teeth.
• Because of its high copper content, malachite will be damaged by jewelers' pickle.

Magnetite

• Hardness 6 to 7
• Also called lodestone.
• This is a black iron ore that is very magnetic. Although we use little for jewelry today, in ancient times this was an important stone.
• It was believed that the stone was alive. To care for it, the owner set the stone in water once a week and "fed" it iron filings. It was taken to mass to drive the devil out of it.
• Believed to dispel melancholy, ease labor, improve memory when worn on the neck, heal sores, and relieve pains in the hands and feet.
• Magnetite assists sexual activities when one partner is anointed with this stone and the other with iron filings.

Moonstone

• Hardness 6 to 6.5
• A feldspar of orthoclase with thin layers of albite. This yields a play of light called adulareseence as light is spread by the fine particles or layers. The effect is a cool frosty glow that accounts for the name of this gem.           
• Occurs in white, gray, pink, green, blue, chocolate and an almost clear variety that looks like a water droplet.
• When worn around the neck, moonstone protects against epilepsy and sunstroke. It is used to treat headaches and nosebleeds.
• When hung on fruit trees it produces abundant crops and generally assists all vegetation.

Morganite

• Har dness 7.5 to 8
• A beryl Discovered in California in 1901, named for JP Morgan in 1910 by GF Kunz, Tiffany's VP & Gemologist.           
• While the color is very deep in large stone it's hard to find deep hues in small stones.
• Recent supplies from Madagascar has produced 2 to 5 carat stones with rich hues.

Onyx

• Hardness 6.5 to 7
• A chalcedony composed of black and white bands. In usage the term often refers to an agate dyed uniformly black.         
• Onyx with brown and white bands is called sardonyx.                                  
• When cut to show concentric circles, onyx forms an eye-like amulet that was worn by the Sumerians, Greeks, Egyptians, and Romans to ward off evil.
• This stone was widely disfavored except when cut as a protective eye. It was said to incite contention between friends, give the wearer broken sleep and terrifying dreams and cool the fires of love when worn around the neck.
• The Arabic name for this stone, "el jaza," means sadness.

Opal

• Hardness 5.5 to 6.5
• From the Sanskrit "upala," gem.                 
• Opal is hydrated silicon dioxide that shows a range of color flashes, usually  including red, blue, green and violet. The play of colors is the result of water trapped in the stone (1-15% by weight). Care should be taken that opals do not dry out. A periodic coating of baby oil is recommended.                                          
• Opals from Mexico & Brazil contain more water and are less stable than Australian opals.
• Opals are thought to possess the virtues of all the stones whose colors appear there.
• The Roman Senator Nonius so valued a large opal that he chose exile rather than surrendering the gem to Mark Antony.
• Types of Opal:
  • Harrlequin - a mosaic of iridescent color.
  • Pinpoint - Multitude of minute specks of many colors.
  • Flash - as above when showing red.
  • Flame - Bright orange-red; translucent to transparent.
  • Fire - bright orange-red; translucent to transparent.
  • Matrix - stone cut so as to leave the opal attached to the rock in which it was formed. This is done to add strength to an otherwise dangerously thin specimen.
  • Doublet - opal glued to a backing of obsidian or onyx to increase color play.
  • Triplet - doublet with rock crystal glued on top to increase lustre and strength.

Pearl

• Hardness 2.5 to 4
• A lustrous deposit formed inside a living bivalve mollusk, often in response to an irritation felt by the animal. Though many mollusks form such deposits, most species do not have attractive surfaces.                 
• Pearls are formed in saltwater and freshwater clams. They are identified by their place of origin, eg. Mississippi River pearls.   
• The largest source of pearls is Lake Biwa in Japan where extensive pearl farming is done.
• Pearls sometimes grow attached to the shell of the animal. These are called blister pearls.                                          
• Cultured or cultivated pearls are made inside a mollusk but have human help to get started. A bit of tissue or a glass or plastic bead is inserted in the animal and allowed to collect nacreous secretions for about 4 years.
• Imitation pearls are much less valuable. They are made by repeated dipping of a plastic bead into a coating made of glue and ground sardine scales. When lightly rubbed on the front of a tooth, the imitation pearl will feel smooth. The genuine (Orient) and cultured pearls will feel slightly rough.
• Pearls are attributed to the Goddess Venus as the symbol of innocence.
• Care should be taken that pearls are not subjected to sudden temperature changes. Wash them in lukewarm soapy water and restring as old cord becomes worn. Knots should be tied between pearls to keep them from rubbing against one another.

Peridot

• Hardness 6.5 to 7
• A transparent gem, sometimes called chrysolite, occuring as pale-to-deep yellow-green.
• Peridot is associated with the astrological sign of Libra and is assigned to the sun.
• In ancient Hebrew writings this stone is linked with the Tribe of Simeon.
• Peridot is believed to cure liver disease and dropsy, to free the mind from envious thoughts, and to dispel terrors of the night. For full magical power, set in gold.

Prehnite

• Hardness 6 1/2
• Can be a ring stone and used as a substitute for nephrite jade for carving.
• Its velvety translucence endear it to cabochon cutting.
• Often found in and is the state gem of New Jersey.                                 
• Found in Mali as a green & bluish-green stone, Australia as a more yellowish stone.

Quartz

• Hardness7
• Quartz is the most common of all minerals.
• Included in this family are amethyst, citrine, flint, onyx, aventurine, jasper, carnelian, rock crystal, agate and crysoprase.

Rock Crystal

• Hardness 7
• From the Greek "krystallos," ice.                
• It was once believed to be hardened ice, and to have the ability to slake thirst.
• Romans drank from crystal goblets and physicians used the stone as an ice pack to ease inflammation of the gall bladder.            
• Indians thought it was the glass of heaven and carved prayer beads from it.
• Crystal has been used throughout history as a reflective surface to concentrate a viewer's consciousness, especially in the form of spheres; i.e. crystal balls. The activity of staring into crystal until the mind becomes receptive to supernatural influences is called scrying.

Ruby

• Hardness 9
• A corundum that occurs as a deep red transparent stone and as an opaque reddish-gray material. In this form it may exhibit a star (asterism) or a single line chatoyancy.
• When flawless, a ruby is more valuable than a diamond.                                   
• Synthetic rubies are produced for jewelry, watch bearings and laser equipment.
• Historically, ruby is associated with royalty and the power of life and death.
• Rubies were attributed the power to prevent loss of blood and strengthen the heart.

Rutile

• Hardness 6.5 to 7
• From the Latin rutilus meaning reddish.         
• A brownish or red stone, occasionally transparent but more commonly opaque.             
• It is best known as an inclusion in other minerals. In quartz, rutile appears as needles of a golden color. These have been given the romantic name of "Cupid's darts." In rubies, needles of rutile are called silk and create star effects.

Sapphire

• Hardness 9
• From the Hebrew sappir.                         
• This form of corundum can occur as blue, yellow, pink, brown, black, lilac and green, both as transparent and opaque, the latter sometimes showing a star (asterism) or cat's eye (chatoyancy).                           
• Until the Middle Ages, sapphires were called hyacinths because of their pale blue color. When it was realized that the mineral occurred in other colors, the term sapphire was adopted for the blue variety while others use a color description; eg. yellow sapphire.
• Sapphires are traditionally connected with the eye and the sky, and therefore with vision and the ability to read the future.
• Sapphires render black magic harmless and help the wearer discern falsehood and guile.

Sardonyx

• Hardness 6.5 to 7
• A kind of chalcedony made brown by the presence of iron. Specifically the name refers to specimens that include bands of white.                                            
• Sardonyx was a popular stone in ancient times and was credited with many powers. The stone was thought to make warriors victorious, protect against poisonous snakes, make a suitor more appealing, neutralize the malign influence of black onyx, increase intelligence and make the wearer fearless and happy, and to protect against witchcraft, sorcery, and incantation.

Serpentine

• Hardness 2 to 6
• An opaque green stone with mottled reddish-brown or milky patches. This with its waxy appearance makes it look like snakeskin, hence the name.                        
• Serpentine is common and occurs in many color and hardness variations. It is used architecturally and to carve objects like bowls and sculptures.
• This stone was believed to protect against snakebite and other poisons and was thought to be most effective if kept in the natural, uncut state.
• Medicine drunk from a serpentine vessel is thought to be more beneficial.

Sodalite

• Hardness 6 to 7
• A popular opaque stone most widely known for its blue color, which somewhat resembles lapiz lazuli. It also occurs in lavender, mauve, yellow- green, green, and pink. Purple shades can fade in sunlight.         
• White and grayish-white mottlings are often found in sodalite; in poor grade material these will be obvious.
• The name of this mineral comes from its sodium content.

Sphene

• Hardness 5 1/2
• Greenish-yellow spheen with flecks of fire from Madagascar hit the market in 2000. Now a better material with orangey body color and high-def dispersion from Pakistan is available.
• Its softness makes it a more pendant/earring candidate than ring.

Spinel

• Hardness 8
• A transparent stone of red (the most valuable), pink, green, blue-green and purple.
• Synthetic spinel is produced in large quantities and is associated with inexpensive jewelry in imitation of diamonds, aquamarine, sapphires, and others. Air bubbles inside the stone often betray these synthetics.

Tiger's Eye

• Hardness 6.5 to 7
• Blue, violet, and golden brown translucent stones showing a silky interior that often iridesces as the stone is rotated. It can sometimes be cut to show a cat's eye.  The effect is the result of asbestos fibers that have been partially replaced by quartz.
• When the fibers are coarse, the stone may be called a hawk's eye.

Topaz

• Hardness 8
• A transparent stone usually of golden yellow but also occurring as pink, red, blue, green and colorless specimens. From Sanskrit "tapas," to glow.                           
• Topaz cleaves easily and therefore requires care in cutting and setting.             
• Some varieties can fade in sunlight.
• In ancient times, the word topaz referred to several other stones and today it is often mistakenly used for smoky quartz and citrine.
• Rubbing or gentle heating of topaz electrifies it causing it to attract small particles like bits of paper or hair.

Tourmaline

• Hardness 7 to 7.5
• A transparent stone of many colors, most notably green, blue-green and pink.
• Often several colors appear side by side. Crystals cut to reveal a pink semicircle with a green rim are called watermelon tourmaline.                             
• Name comes from the Sanskrit "turamali."
• Tourmaline is dichromatic; it shows a bright color from one direction but will look almost black when seen from the side. Like topaz, this stone will hold static electricity if it is rubbed or gently heated. Together these two tests provide identification.

Turquoise

• Hardness 5 to 6
• A blue or blue-green stone, usually opaque but occasionally translucent. 
• From French "Pierre Turquoise" which means Turkish stone, a reference to its popular use in Turkey. Arabs call it "fayruz" or "firuzaj," the lucky stone.
• Blue material will turn green when it absorbs oil from the skin. After polishing, most turquoise is sealed with a plastic that soaks into the stone and closes the pores.         
• Reconstituted material (bits of turquoise compressed with adhesive) is sometimes used in cheap jewelry. To test a sample, lay a hot needle against the stone. If it contains adhesive, the resulting smell of plastic will give it away.
• Some pieces of turquoise are cut so as to contain some of the rock in which they were o formed. This is called matrix turquoise. Some varieties show fine dark lines running throughout the stone; this is called spiderweb turquoise.
• Turquoise is thought to protect the wearer from poison, bites of reptiles, and diseases of the eye.
• Some people think these powers are in force only if the stone was received as a gift
• Giving a turquoise is also said to improve its color.
• Since the thirteenth century this stone was held to give sure-footedness to a horse. The idea was later enlarged to protect against all falling.

Zircon

• Hardness 7 to 7.5
• A transparent brittle stone occurring as brownish or green material, usually heated to turn pale yellow and blue. It can be found naturally colored as orange-red (most valuable), purple, reddish-brown and brownish-yellow.
• Because its brittleness makes it difficult to cut, stones of more than a couple carats are rarely seen.
• Zircon is said to drive away evil spirits and bad dreams, banish grief and melancholy restore appetite, induce sleep, and protect against lightning.

Zirconium (cubic)

• Hardness 8.5
• A transparent singly refractive, manmade gem produced from the element zirconium.
• It is available in many colors, as well as a bright white that resembles diamond.
• Because of its "fire" and low cost, CZ has replaced yag (synthetic garnet), spinel, and strontium titanate as a diamond substitute.