Gemstones

It is quite common for travellers to buy gems or finished jewellery during a trip. Often price and selection are better in places where stones are mined, cut or set than elsewhere. Caution is required since some vendors are positively predatory, especially in tourist areas. Bargaining is often needed to get a good price, even from an honest vendor.

It does not always apply, but the phrase "touchstone markup" is used in the gem trade. That is a 100% markup; the price will double for every set of hands the stone passes through. Sometimes this means that the price difference between buying at or near the source and buying elsewhere is enormous.

Some travellers also dig up gems themselves; see Rockhounds.

Understand
As with any goods that span a wide range of prices, it is safer to avoid the big-ticket items unless you are either an expert yourself or have expert advice, dealing with a large reputable vendor will reduce the risk, and "tourist trap" stores should be avoided. See shopping for other general advice.

If you plan to bring home expensive jewellery, check your country's import regulations. Some countries, such as Canada, charge a stiff duty on finished jewellery but much less on unmounted stones. In those cases it may be better to buy cut and polished but unmounted stones and have a craftsperson back home mount them. Sometimes it is possible to bring some extra stones and trade them for the labour.

Pricing
Stones are sometimes classified as precious (diamond, ruby, sapphire and emerald) or semi-precious (everything else) and prices generally reflect this, though some semi-precious stones are also quite expensive. Both the quality and the size of stones can greatly affect their price; stones that are large, flawless or both may be rare and expensive. Colour is often a factor; many gems come in a range of colours depending which impurities are present. Murkiness, inclusions (other minerals within the stone, often giving dark or opaque areas), or flaws (cracks, empty spaces, crystal boundaries if the stone is not from a single crystal, or other irregularities) can greatly reduce the value of a stone. Pointing these out may be helpful in bargaining.

Stones are generally priced by weight, measured in carats; five carats is one gram. Within the range of common sizes, the weight/price relation is linear; if for some gem a 1-carat stone is $100 then a 10-carat stone will be about $1000, provided such stones are reasonably common. However if stones above 5 carats are rare, then a 10-carat stone may be considerably more than $1000 and the price of a 20-carat stone is likely to be astounding. Exceptionally large stones are often sold at auctions where only museums and millionaires can afford to bid.

If one stone is just a scaled-up version of another (multiply length, width and depth by the same constant), then the volume and weight are proportional to the cube of the diameter. A stone that is twice the diameter of another will then be about eight times the weight and price. Of course this is not always the case; a larger stone may be cut proportionally thinner (less depth) than a smaller one.

Several smaller stones in a piece of jewellery may be a better buy than one large one; it is common to see three sapphires in a row across a ring or one moderately large stone with several smaller ones around it. For example, three stones of 5mm diameter will usually have total weight, and therefore cost, considerably less than a single 8mm stone (3*53 = 375 is less than 83 = 512), but the total surface area they display will be slightly larger (3*52 = 75 is more than 82 = 64). Also, smaller stones are less likely to be seriously flawed; a cutter working on a raw stone that has a flaw might either produce a large but flawed finished stone or cut around the flaw to get several smaller unflawed stones.

Hardness
The Mohs scale of hardness uses various minerals to define its levels; the top four are diamonds 10, corundum (sapphires and rubies) 9, topaz 8, and quartz 7. These are hard enough for any use; in particular they can be used in a ring with no fear of damage if the hand bangs against something. Other hard stones — such as beryl including emeralds (7.5–8), spinel (7.5-8), tiger eye (7) or garnet (6.5–7.5) — can also be used anywhere. Rose quartz, clear "rock crystal", citrine (yellow or brown) and amethyst (purple) are varieties of crystalline quartz with different colours from different impurities; all have hardness 7. Agate and jasper are mostly quartz and have hardness 6.5 to 7.

Moderately hard stones &mdash; moonstone (6-6.5), opals (5.5–6.5), turquoise (5–6), labradorite (6–6.5), sodalite (5.5–6), diopside (5–6), lapis lazuli (5–6) and obsidian (volcanic glass, non-crystalline quartz) (5-5.5) &mdash; are less than ideal for rings or bracelets. They are fairly often used in those, but there is some risk they will scratch, chip or crack if they hit something. It is safer to get them in some other piece of jewellery; earrings and pendants are popular choices. The shape of the stone and the design of the setting affect the risk; a stone that sticks out is much more likely to be damaged than a flat one or one protected by the setting.

Stones with hardness below 5 should be used only where they are unlikely to get banged about, in particular never in rings. Examples include flourite (4), pearls (2.5–4.5), coral (3–4), malachite (3.5–4), rhodochrosite (3.5–4) or amber (2–2.5).

Stones
Gems are found all over the world, but some places are famous for certain types.



A few types of gemstone are found only in quite limited areas. They are likely worth looking for if you travel there.
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 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
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 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
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 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg
 * Ammolite from Placenticeras fossil ammonite, Alberta.jpg

See pearls and paua shell below for other items found in only a few places.

Rubies and sapphires
Rubies and sapphires are the same mineral, corundum (hardness 9); different impurities give different colours. Red ones are called rubies; any other colour is a sapphire, but the most prized sapphires are intensely blue. The top-grade stones are very clear and can be cut with facets; lesser stones are cut cabuchon (curved, not faceted) to give star rubies or star sapphires.

Sri Lanka is known for sapphires, Myanmar for rubies, and India has some of both. There are also rubies in Greenland and Nunavut.

Off-color stones &mdash; most commonly grey, but also burgundy, pale blue, pink or brown &mdash; are much cheaper than bright red or blue stones and may still be lovely. Burgundy "plum stars" are common in Agra; they usually have a lot of inclusions (about a third of the stone is black), but they can be quite pretty and are remarkably cheap compared to other rubies. Sri Lanka has many grey star sapphires, also relatively cheap.

Black or green star sapphires are rare and command a high price; they have a six-point star like any other sapphire. A "black star" which has only four points is a semi-precious stone called diopside, and should be far cheaper. Some vendors may try to sell tourists black stars at sapphire prices; walk away quickly.

Historically, some red spinels were also called rubies, but gemologists now reserve the term "ruby" for red corundum.

Jade
Jade has been an important stone in many cultures throughout history. It is used not only in jewellery, but also in carvings, statues, tools, weapons and even for household objects like bowls. The Liangzhu Culture in China (3400-2250 BCE) is known mainly by the high-quality jade artifacts it left behind, and many other groups &mdash; especially other parts of China, Southeast Asia, Mexico and Central America, and the Maori of New Zealand &mdash; used jade.

There are two distinct minerals that are called jade; nephrite is more common, jadeite often more valuable. Most Chinese and all Taiwanese and Canadian jade is nephrite; most Burmese and Mexican jade is jadeite. There are still some good Chinese sources for jade, notably Khotan, but today most of the best jade in China is imported from Myanmar (Burma). The border town Ruili has much jade, but for the best deals, go to Myanmar. Taiwan also continues to produce some jade, with much of the mining being concentrated in the area around Hualien, and numerous jade shops in the city where you can purchase local jade products.

In Myanmar, the city of Mandalay has a jade market where you can watch merchants haggling over the price of jade at all stages of production. You can even purchase some jade trinkets yourself, but be prepared to haggle, and if possible do some homework beforehand to have some idea of what prices should be.

British Columbia (Canada) is also famous for jade; the sprawling Jade City store on the Stewart-Cassiar Highway in northern BC is a great experience for jade fans, but you can find better deals in Vancouver.

There are other stones which may be used instead of jade, including serpentine or "false jade" and "greenstone", a general term applied to several different minerals.

Pearls
Almost every tropical seacoast area has some pearls, hard objects produced by various aquatic mollusks. Places known for their pearls include Tahiti, Bahrain, Mexico, India, Indonesia, Myanmar and the Philippines.

Pearls are not hard enough for all applications; the most common uses are in necklaces and earrings. Good pearls are not cheap, but they are much less than some other gems; a fine pearl necklace will be expensive, but one with the same number and size of emeralds might bankrupt a small country.

The best-known type is produced by various species of oysters and made of a substance known as nacre or mother-of-pearl, giving it its distinctive iridescent appearance. Natural pearls are rare and expensive; the vast majority of pearls on the market today are cultured pearls, made using a technique which originated in Japan but is now used in many other countries.

China has freshwater pearls, made by a species of freshwater mussels, and usually cheaper than saltwater pearls. These are also made of nacre.

There are several types of pearl not made of nacre:
 * The conch pearl &mdash; produced by the queen conch, a marine mollusk found only in the Caribbean, in particular the Bahamas &mdash; comes in various colours. The most highly-prized ones are pink and porcellaneous, with a distinctive "flame structure" appearance that resembles a fire burning on the surface.
 * The melo melo pearl, made by the melo melo snail, which is found in the South China Sea and Andaman Sea, in the waters off the coasts of the Philippines, Vietnam, Cambodia, Thailand, Malaysia, Indonesia and Myanmar. Like the conch pearl, the most prized ones have a porcellaneous "flame structure" on the surface, but they are orange instead of pink.
 * The quahog pearl is produced by a species of clam found off the east coast of Canada, the United States of America and Mexico, with the most prized ones having a purple hue.

Unlike oyster pearls, these have never been cultivated, so they are rare and expensive.

Mother-of-pearl
"Mother-of-pearl", the lining of mollusk shells (including some from species that do not produce pearls), is also used in various decorative arts including jewellery. Large pearls are rare and expensive, but it is relatively easy to get a large chunk of mother-of-pearl; just find a big shell and cut it to suit the requirement.

Mother-of-pearl is often used in inlay work on furniture or other household items. In China. wooden Go boards with mother-of-pearl inlay for the lines are fairly common.

Museums
Almost any natural history museum worldwide will have a geology section, often including some gems. Some mines and many mining towns or regions also have museums with gems.

Some famous gems are in museums:

Ethical concerns
There are two important ethical concerns you might consider in regard to buying gemstones.

The first is the destructiveness of mining practices. For example, some diamond mines are of the open pit variety, which can cause irreversible environmental damage. In other places, mine safety is a serious problem. Some gems, such as quartz, may be mined by families digging deep in the dirt without any safety equipment or any way to prevent the tunnels from collapsing. What they dig out is usually sold for a pittance to distributors, who then sell the stones at a much higher price to wholesalers and tourists.

The second is that the value of the gemstones has made mines attractive to governments, terrorist groups and criminal organizations that use the profits they receive from the sale of these stones to finance brutality, torture, murder and other crimes against humanity. There have been some efforts to combat what are called blood or conflict gemstones and diamonds, but due to the lucrativeness of the industry, these are often smuggled across borders and find their way onto the markets of wealthy countries, anyway.

Stay healthy
You should avoid wearing gemstones and crystals with magnetic charges if you have implanted medical devices such as pacemakers and defibrillators as they may interfere with these devices. Magnetic gems include magnetite, hematite, shungite and pyrrhotite. Watch out for any stone which contains iron.

Working with some gems can be hazardous. Malachite, for example, contains mercury and can emit dangerous fumes when being cut or polished. Like any heavy metal poison, mercury generally causes no obvious immediate symptoms but it remains in the body indefinitely and can cause long-term damage. Both digging for the stone and wearing malachite jewellery, though, are entirely safe.

Gemstone Commons:Category:Gemstones