2 Precious Metals Naturally occurring Metallic elements Rare Valuable Chemical attributes of a metal: solid, ductile, malleable, luster (shine), conducts electricity, also these are less reactive (more stable) than many elements
3 Precious Metals Graded on: Rarity Purity Mass Purity often 99.9%, approaching but can never reach 100%Bullion = precious metal in bulk, value by weight, after refining but before processing into ingots (bars) or coins
4 Precious Metals Silver: current value $22.38 per ounce Gold: current value $ per ounce1 troy ounce = about 31 gramsPrice fluctuates according to supply and demand and other economic conditionsNot going to say much about platinum, extremely rare, often found mixed in with other metals in alluvial deposits, mainly industrial applications, currently valued at $1399 / ounce
5 Silver Uses: coins, jewelry, mirrors, silverware Found in ores with other elementsExtracted through miningMajor mining operations in Peru, China, and MexicoOther large mining operations are found in Australia, Bolivia, Russia, the US, Poland and Canada, also Argentina and Chile.In the United States, Nevada is the largest producer.Highest electrical conductivity, but more expensive than copper so not often usedThough sometimes wires can be silver-platedUsed in film photography, electronics, musical instrumentsMost often collected as a by-product of mining for other metals like copper, lead, zinc, or goldThe largest silver nugget ever mined, weighing over a ton (900 kg), came from the Smuggler Mine in Colorado. At its peak the mine was responsible for nearly one-fifth of the world's total silver outputHistorically, silver has been mined in Peru, Mexico, and Bolivia since the 1500’s
6 GoldUses: coins, jewelry, space research and other scientific advances, dentistry, electronicsNative gold is often found as an alloy with silver.Extracted through mining, “panning for gold” in river sedimentsChina and Australia are the biggest producers of gold.Other major gold mining operations take place in the US, Russia, and South Africa, also South America, Canada, and Indonesia.Gold can be found throughout the country. Mines in South Dakota and Nevada supply the majority of the gold in the United States.24k (carat) gold is considered pureAlloys used to make it harder when used in circulated coinsBefore this, people would bite the coins to see if they were genuine goldCan take many different forms from flakes to ropey texture to nuggets
7 Gold Rush!Gold was first discovered in the US at the Reed Gold Mine in North Carolina in 1803.After that, gold rushes took place in Georgia, California, Colorado, and the Black Hills.Similar gold rushes took place in New Zealand, South Africa, and the Klondike region of Canada.Gold is found all over the world
8 Famous Finds Holtermann Nugget found by Bernhardt Holtermann in Australia in 1872weighed in at just under 640 lbs.This one was found in a hard rock mine, so not really a nugget per se
9 Famous Finds Welcome Stranger found by John Deason and Richard Oates in Australia in 1869weighing in at 2316 troy ounces (about 159 lbs.)Welcome Stranger was melted down, it may have been bigger but they had to break it down to weigh itThey got over 2200 ounces out of it once it was refined
10 Famous Finds Hand of Faith found by Kevin Hiller in Australia in 1980 876 troy ounces (almost 62 lbs.)Using his metal detector outside his trailer in Victoria, AustraliaThe story goes he got a signal, but thought his detector was acting up, so almost didn't dig!Sold it to the Golden Nugget Casino in Las Vegas for a million dollars, where it is now on display
11 Mining Sluicing Dredging Hard-rock mining Some of the oldest known gold artifacts date between 4700 and 4200 BC, indicating that gold mining could be at least 7000 years old.Panning for gold not feasible on a large scale, only works when gold nuggets are large enough to be visible, mostly a tourist attraction todayRocker boxes used where water level is low, otherwise like sluicingHard-rock mining may be in open air pits or up to 12,800 ft underground (requiring AC for people to work there) as in South AfricaThis is where most gold comes from today rather than placer mining (from river deposits)Can also be gathered as a by-product, as in Indonesia’s largest copper mine, which also produces a lot of gold
12 Processing Grind rocks containing gold. Add sodium cyanide to dissolve it.Collect the new gold cyanide solution and add zinc to form a precipitate.Add sulfuric acid to remove the zinc.Collect the gold sludge and put it through a smelting process.Ship the gold to a metal refinery for final processing.Smelting is heating and extractingEnvironmental concerns with pollutionSome processes use mercuryWith silver, it is often found with lead, and differences in solubility allow it to be dissolved in zinc which separates it from the lead, then zinc is evaporated and silver remainsThis is called the Parkes process and is more efficient and less hazardous than other methods, including those used in gold miningElectrolysis with copper can also be used to extract silver
13 ProcessingThere, it is melted again and borax and soda ash are added, to remove unwanted impurities.Depending on its intended usage, the pure gold is then mixed with other metals to form an alloy.Gold ingots are formed.Pure gold is 24k12k would be half gold, half some other metalThe alloy is harder and more durable than pure gold, also adds color which we see in the jewelry trade
14 Precious Gems Pretty minerals used to make jewelry Graded based on ColorCutClarityCarats (size)Usually minerals, but some come from organic sources (like pearls)Intense colors are valuedIn diamonds, it is the cut and clarity that are most important, making it sparkleClarity = purity, few to no inclusionsHere, lab-created stones are the bestCarat = 200 mg or 0.2 gramValue depends on the rarity of the gem as well as its qualityVaries according to consumer market demands, or whatever is fashionable at the timeCan be tens of thousands (or more) per caratPrecious gems are more rare than naturally occurring metalsThey take a long time to formThey are found in oldest parts of a continentPolitical situation also influences which areas are accessible
15 Precious Gems Precious gemstones Diamond Ruby Emerald Sapphire The term comes from ancient Greece, and does not necessarily reflect which gems are the most rare and valuable
16 Diamond Formed from pure carbon Hardest known material Used in jewelry as well as in cutting and polishing toolsFormed under high temperature and pressure beneath the Earth’s surface, over a long period of timeDerived from Greek “adamas” = unbreakableIts beauty comes from the structure of the crystal lattice1,652 and 2,372 °F temp, 45K – 60K atmospheres of pressure, miles below the surface, in Earth’s mantleTime period is 1 billion to more than 3 billion yearsTypically, diamonds come from continental cratons (core of the continent, where crust is thick enough for diamond formation)volcano must reach deep enough to spew out the mineralsOften, miners find indicator minerals to lead them to diamond minesFew are rich enough to be economically viable
17 Diamond Primary source: brought up by volcanic activity Secondary source: dispersed by erosionIt is thought that diamonds were first recognize in India, between 3,000 and 6,000 years ago in alluvial deposits
18 Diamond Mining 1725 was the first diamond discovery outside of India Ore is crushed, then diamonds are sorted by density.The raw diamonds are traded or sold.Raw diamonds are then hand-picked, cut and refined.1725 was the first diamond discovery outside of IndiaThen the extraction from primary deposits started in the 1870’s and has increased since thenThey are mined from kimberlite and lamproite volcanic pipes
19 Diamond MiningToday, the most productive diamond mining operations are in Africa, Russia, Australia, and China.There are also productive diamond mines in India, Canada and Brazil.In the US, diamonds have been found in about a third of the states.Approximately 130,000,000 carats (26,000 kg) of diamonds are mined annually, with a total value of nearly $9 billionRoughly 49% of diamonds originate from Central and Southern AfricaFound mostly in the interior parts of the US, where the continental craton is (the oldest part of the crust)
21 Diamond Mining Blood diamonds Kimberly Process established by UN in 2002 aimed to reduce sale of conflict diamonds, so the money can’t be used by rebel leaders to fund their wars and revolutionsCanada has stricter rules and enforces conflict free diamondsHard to trace stolen diamondsThey can be marked but marks are just as easily removed
22 Diamond Color in diamonds comes from impurities. Synthetic diamonds Nitrogen is the most common and creates the yellow and brown color of most diamonds.Synthetic diamondsAlmost diamondsSynthetics use HPHT (high pressure, high temperature) process or CVD (chemical vapor deposition)Many for industrial uses, not as popular in jewelry, but colorful ones are often lab-grownCubic zirconia or silicon carbide (less common) are synthetic simulants that look a lot like diamonds
23 It’s largest dimension is just over 4 inches in length Famous FindsThe Cullinan diamond is the largest gem-quality diamond ever found, at carat (about 1.37 lb.) rough weight.It was found in South Africa in 1905.It’s largest dimension is just over 4 inches in length
24 Originally thought worthless for its color Famous FindsThe Golden Jubilee is the largest faceted diamond in the world.At carats, it is larger than the Cullinan I, the largest diamond cut from the Cullinan raw stone, though it came from the same legendary mining grounds.Originally thought worthless for its colorHenry Ho of Thailand bought it in 1995 and gave it to the king of Thailand in celebration of his 50th anniversaryValued at $4-12 million
25 Famous Finds Possibly the world’s most famous diamond Valued at $250 millionIt has a long recorded history, dating back to the late 17th century.It has changed hands numerous times, from the kings of France to its home at the Smithsonian in the United States.Supposedly cursed45.52 carats, about the size of a walnut or a pigeon eggThought to be cursed because of the fate of its owners, in particular, Louis XVI, who was executed during the French Revolution.It was stolen at the end of his reign and during the intervening years it was transformed from the French Blue of the crown jewels to the Hope diamond we know today.
26 Famous FindsThe Patiala necklace featured 2,930 diamonds, including the 428 carat De Beers diamond as its centerpiece.The necklace disappeared in 1948.When it was recovered 50 years later, the largest diamonds were missing.The Patiala Necklace was a necklace created by Cartier in 1928 for the Maharaja of Patiala. It contained 2,930 diamonds, including as its centerpiece, the world's seventh largest diamond, the 428 carat De Beers. The necklace disappeared around Part of it was recovered fifty years later with the De Beers diamond missing, along with many of the larger stones.
27 Recent NewsA flawless 59.6-carat pink diamond will be auctioned in Geneva this fall at a record asking price of $60 million dollars.The gem, which is known as the “Pink Star,” was mined by De Beers (a major mining conglomerate) in Africa in 1999.It received the highest possible color and clarity rating from the Gemological Institute of America (GIA).It weighed carats in the rough, and was cut and polished over a period of two years by Steinmetz DiamondsPink diamonds of 5 carats are rare, this is unheard of!De Beers is a family of companies that does a lot of mining in AfricaThe same group that uncovered the previous record-breaking diamonds
28 Ruby Crystals formed by the mineral corundum (aluminum oxide) Red color comes from the element chromiumColor is the most important factor in determining a ruby’s value.After color come clarity, size and cut.Rutile (titanium dioxide) needle inclusions found in all natural rubiesCan form a star pattern or reflect light in a special way, increasing the value of the ruby“pink sapphire” is basically a rubyChromium is rare so rubies are specialOne of the most remarkable things about the formation of rubies is that geologists are not sure how it happens.The commonly held belief amongst geologists is that rubies are formed by tectonic plates smashing together – as did the India and Asia plates when the Himalayan mountains were formed around 50 million years ago – forcing limestone deposits deep into the earth where intense heat and pressure metamorphosed the limestone into sparkly marble. At the same time, molten granite bubbled up into the marble and removed the silica but left behind the aluminum through a process called metasomatism.The problem is, and the part that is confusing geologists, is that although the ruby-hosting marble extends over large areas of the Himalayas, the rubies themselves only appear in sporadic, localized patches. There must be some other missing piece of the puzzle that determines why and where rubies will form in this marble.This confusion was compounded by the discovery of some of the world’s most impressive rubies in the Mogok mine in Myanmar (formerly Burma). Whilst the rubies were hosted in marble, they were found alongside topaz and moonstone, minerals that are igneous rather than metamorphic in origin. This has confused geologists further and it may be many years before they find a final definitive explanation for how these beautiful gemstones are formed.
29 Ruby Myanmar region famous for rubies Most rubies come from Asia and Africa.Rubies have also been found in Australia, Greenland, Brazil, and the US.The term “pigeon’s blood” is used to describe the rich, red color of Myanmar rubies (former Burma, so OK to call them Burmese rubies)US rubies found in MT, WY, and the CarolinasIn Europe, Macedonia is the only place where rubies have been foundBurmese rubies becoming scarce
30 Mining Gems Blasting Digging Dredging You’ve got to look in the right place first, which depends on what you’re afterMost gems are minerals deposited by water or volcanismUse the surrounding rock to indicate site and depth for digging, often in oldest parts of continental crustSo… not Oregon, folksModern tech like tractors and pneumatic feather and wedge drilling systems make it easier than shovels and mine cartsDredging is going through the rubble like panning for gold
31 A lot like mining for silver or gold point out ventilation system
32 Ruby Rubies may be altered before they are used in jewelry. Heat treatmentimproves colorremoves inclusionsRepairing crackslead glass used to fill fracturesHeat degrees FTo fill cracks:The ruby is dipped into oils, then covered with powder, embedded on a tile and placed in the oven where it is heated at around 900 °C (1600 °F) for one hour in an oxidizing atmosphere. The orange colored powder transforms upon heating into a transparent to yellow-colored paste, which fills all fractures. After cooling the color of the paste is fully transparent and dramatically improves the overall transparency of the ruby
33 Ruby Synthetic rubies can be produced. Used in red lasers But if they are absolutely perfect then it’s obvious they aren’t natural rubies b/c all rubies have inclusions
34 Famous RubiesA ruby recently found in Greenland may be the world’s largest rough ruby. The crystal weighs 8.2 lbs. or 18,696 carats.Offered for sale by a company called 125West
35 Famous RubiesAmerican billionaire Lily Safra’s ring, containing The Hope Ruby (a Burmese ruby of carats) was sold at auction in 2012 for $6,742,440.A ring belonging to Elizabeth Taylor which featured an 8.24 carat gem sold for $512,925 per carat (over $4.2 million in total) at an auction in 2011.
36 Star Rubies The Midnight Star 116.75 carats Natural History Museum in NYCToday, out of every 100 rough corundum (ruby and sapphire) mined; only three will have stars apparent after being cut into cabochons. Out of these three, one will have a poor color but a good star; one will have a poor star but a good color and only one out of hundred will have both a good star and a good color! Most original sources of star rubies such as Mogok (Burma) & Vietnam have run out of supplies. Worldwide production today is yielding a very small quantity of fine stars (especially in sizes above 5 carats). Star rubies are becoming rare as most rough ruby today is cut into faceted stones after heating instead of being cut into cabochons to display the star.Stars called “asterisms” formed by rutile inclusions
37 Star Rubies Delong Star Ruby 100.32 carats Natural History Museum in NYCIn 1964 the Delong Star Ruby was the object of an infamous burglary, carried out by Jack Murphy, known as Murph the Surf, and two other men. It was then ransomed and recovered. The Delong Star was found at a designated drop off site - a phone booth in Florida.
38 Star Rubies Rosser Reeves Ruby 138.7 carats Donated to the Smithsonian in 1965He bought it and had it polished, which removed some material but re-centered the star and made it even more beautiful
39 Sapphire Crystals formed by the mineral corundum Traces of titanium and iron produce the blue color.Other colors created by different chemical impuritiesSome corundum crystals used in watches, shatter resistant windowsAlso used as insulators in semiconductors
40 Sapphire Form as molten rock cools slowly beneath the Earth’s surface Mined from primary sources (underground) or from alluvial depositsMost of the world’s sapphires come from Asia and Africa.Other major sapphire mining operations take place in Australia, Brazil, Greenland, and North America.Forms in coarse grained igneous rocks that do not have much silicaIn North America, Montana produces the most sapphiresMadagascar produces a lot as well
41 Sapphire Sapphire is mined in much the same way as ruby. It is treated prior to being used in jewelry.Diffusion treatments may enhance a sapphire’s color.Heat treatment as in rubiesYogo Montana sapphires may not require treatment, pristine and beautifulDiffusion treatment: Beryllium is diffused into a sapphire under very high heat, just below the melting point of the sapphire
42 Famous Sapphires Millennium Sapphire Discovered in Madagascar in 1995 The world’s largest sapphire, at 61,500 carats in weight
43 Famous Sapphires Logan sapphire 423-carats National Museum of Natural History in Washington, D.C.One of the largest faceted blue sapphires in existenceSurrounded in a diamond setting
44 Famous SapphiresThe record price-per-carat for sapphire at auction was achieved by a sapphire from Kashmir in a ring, which sold for more than $175,000 per carat (more than $3.4 million in total) in May of 2013.
45 Star Sapphires Black Star of Queensland The largest gem-quality star sapphire in the world733 carats
46 Star Sapphires The Star of India 563.4 carats Museum of Natural History in NYC
47 Star Sapphires The Star of Bombay 182-carats National Museum of Natural History in Washington, D.C.
48 EmeraldEmerald is formed by the mineral beryl with chromium or vanadium inclusions.Minerals dissolved in hot water beneath the Earth’s surface cool and slowly form crystals.Color and transparency are the most important attributes.BERYL = beryllium, aluminum, silicon, and oxygenAssociated with pegmatite or calcite
49 Emerald Emeralds are found all over the world. Columbia is by far the world's largest producer of emeralds.In the US, emeralds have been found in Montana, Nevada, Connecticut, and the Carolinas.More recently, emeralds have been found in the Yukon.90-95% from Columbia
50 Emerald MiningMining is done in two ways: a process called open pit mining (which is not used very often due to environmental problems), and the other process is through tunneling following the white calcite veins with possible emerald crystallization. Gem mining is very difficult, but Emerald mining is even more difficult because contrary to others, which are also found in the river beds, emeralds are found only in their original growth pockets.Open pit mining produces tailings / slurry that can be harmful to the environmentOr erosion concernsWater pollution can be a concernSometimes when they are finished mining, the land is converted to a landfill
51 EmeraldEmeralds are often enhanced before sale by adding oils which improve their luster.Need to disclose report of any enhancements made
52 Famous Emeralds Patricia Emerald Found in Colombia in 1920 632 carats Special because the crystal is 12-sided Named after owner’s daughter
53 Famous Emeralds Gachala Emerald found in 1967 in Colombia 858 carats now at the Smithsonian
54 Famous Emeralds Duke of Devonshire Emerald Discovered in Columbia Presented to the duke of Devonshire in 1831carats
55 Famous Emeralds Teodora emerald This 57,500 carat stone may be the world's largest cut emerald.Up for auction, expected to bring a price of $1.15 millionOriginally found in BrazilCut in IndiaBought by Reagan Reaney in Calgary, BC who is auctioning itThere are doubts as to how much of it is real emeraldIf it doesn’t sell, it will be donated to Gemological Institute
56 Famous Emeralds Bahia emerald At 840 lbs., the largest single emerald crystal ever foundValued at $400 millionFirst discovered in Brazil in 2001Found in a storage basement in New Orleans after Hurricane KatrinaReported stolen in 2008 from a secured vault near Los AngelesAt one point, it was listed on eBay with a Buy it Now price of $75 million!Several competing claims of ownershipEventually, the emerald was taken into the custody by the Los Angeles Sheriff's Department. The case will be decided in court in 2013.It’s like 1.9 million carats
57 Famous Emeralds Chalk Emerald Columbian emerald 37.82 carats Belonged to a noblewoman in IndiaIn the 20th century, the emerald was recut and set in a ring designed by Harry Winston Inc.The Chalk family donated it to the Smithsonian in 1972.Surrounded by 60 diamonds totaling 15 carats
58 Famous Emeralds Mogul emerald 217 Carats Originally from Columbia Cut and sold in India to a Mogul nobleEngravings date back to late 1600’sSold at an auction in 2001 for over $2 millionNow in a museum in Qatar
59 Famous Emeralds Imperial Emerald 206 carats Amazing color and transparency, completely unenhancedBeing offered for sale by New York company Bayco Jewels at the gem exhibition in Switzerland this year
60 Pearl Calcium carbonate deposits formed by shellfish Found in freshwater and marine environments around the worldJapanese pearls, Indonesian South Sea pearls, and Tahitian pearls are the most famous.
61 Pearl Pearls may be natural, farmed, or imitation. Of these, natural pearls are the rarestPerfectly round and shiny pearls are the most desirable.Colors may vary from white or cream to yellow, pink, or black.The color of pearls is determined partly by chemistry and environmental factors, but primarily by the species of mollusk that produced it (the pearl being the same color as the mollusk’s mantle). Black pearls used to be rare, but now they are being farmed, so one color is not necessarily more valuable than others.Real pearls can be dissolved by acidX-rays show layers of development in real pearlsPlastic ones are perfectly smooth and round, real ones have a slightly gritty surfaceIn addition to being used in jewelry, pearls have also been used in cosmetics and in paint
63 Famous PearlsThe Pearl of Lao Tzu (also known as The Pearl of Allah) is the largest known pearl.Recovered from a giant clam in the Philippines in 1934The pearl is 9.4 inches in diameter and weighs about 14 lbs.this pearl is valued at $3.5 million due to its astounding size
64 Famous Pearls Other famous pearls include necklaces worn by royalty. Rare necklaces have sold at auction for $1-3 million.A necklace worn by the Baroda nobility of India sold for over $7 million.Known as the gem of queensHard to find natural pearls of matched size, which is one reason why whole necklaces of natural pearls are valuableAlso adds value if it was worn by someone famous