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Showing posts with label Gemstone Jewellery. Show all posts
Showing posts with label Gemstone Jewellery. Show all posts

Thursday, August 19, 2010

Advice for Buying Diamonds and Colored Gemstones

Celebrating a Special Occasion with Jewelry

Jewelry and gems, The Buying Guide

Colorful choices in colored Gemstones

Important advice before you buy colored gemstone

What to ask when buying the gemstone

Asking the right questions is the key to knowing what you're getting when it comes to buying gemstones. It is also the only way you can be sure what you are comparing when considering gems from different jewelers. Be sure the jeweler can answer your questions, or can get the answers for you. Then, be sure the jeweler is willing to put the answers in writing on your bill of sale. Finally, verify the facts; double check that the stone is as represented, by having it examined by a qualified gemologist appraiser. In this way you'll have no doubt about what you are getting, and you'll begin to develop a solid relationship with the jeweler from whom you make the purchase, based on confidence and trust. And, in the event the stone is not as represented, you'll know in time; and have the information you need, to get your money back.

Questions to ask when buying a diamond

You should always have very specific information before purchasing a fine diamond weighing one carat or more. For smaller stones, the information may not be so readily available, since most jewelers don't take the time to grade them precisely. An experienced jeweler, however, should be able to provide information regarding quality for stones from a half carat and up, or offer to find it for you. Indeed, some laboratory are now providing grading reports for diamonds from 0.47 carats and up.
Also keep in mind that since it is not possible to grade mounted diamonds accurately, we recommend that fine diamonds weighing one carat or more be purchased unmounted, or moved from the setting and then remounted. In jewelry containing numerous small diamonds, the stones are graded before they are set and information may be on the sales tag. If not, it is extremely difficult to know for sure what the true quality is, and much can be concealed by a setting. We recommend buying such pieces only from a knowledgeable jeweler with a good reputation.
Here are the basic questions to as and information that needs to be included on the bill of sale of your diamond:

1. What is the exact carat weight? Be sure the stone's weight is given, not its spread.

2. What is its color grade? And what grading system was used?

3. What is its clarity (flaw) grade? Again, ask what system was used?

4. What shape is it? Round, pear, marquise?

5. Is it well cut for this shape? How would the "make" be graded: ideal, excellent, good?

6. What are the exact millimeter dimensions of the stone?

7. Is this stone accompanied by a diamond grading report or certificate? Ask for a full report.

Be sure to find out what system was used to grade the stone. If GIA terms are used, ask if GIA standards and methods have been applied to grading the stone (Diamond).

Be sure to get the exact millimeter dimensions of the stone; the dimensions can be approximated if the stone is mounted. For a round stone, be sure you are given two dimensions for the stone's diameter; since most are not perfectly round, you need the highest and lowest. For fancy shapes, get the dimensions of the length and width. Always get the dimension from the table to the culet as well, that is, the depth the stone.

Be especially careful if the diamond is being taken out on consignment, on a jeweler's memorandum or sale slip, or on a contingency sale. Having the measurements in writing helps protect you from being accused of switching should you have to return the stone for nay reason.

Always ask if the stone has a certificate or diamond grading report and, if so, make sure it accompanies the stone; if you are taking the stone (diamond) on approval, ask for a copy of the report. If there is no report or certificate, find out who determined the color and flaw grades; make sure the seller puts that information on the bill of sale, and insist that the sale be contingent upon the gemstone's actually having the grades represented.

Additional questions to help you make your selection

Is it large enough?

This is a valid question and one you should be honest with yourself about. If you think the diamond is too small, you won't feel good about wearing it. Remember that such other factors as clarity and color can be judged several grades with little visible difference, and this might enable you to get a larger diamond. And remember that the color and type of setting can also help you achieve a larger look.

Does this diamond have a good make?

Does this stone have good proportion? How do its proportions compare to the "ideal?" Remember, much variance can exist and a diamond can still be beautiful, desirable gem even if it does not conform to the ideal.

Nonetheless, you won't want a diamond with poor proportions, so if you have any question about the diamond's brilliance and liveliness; if it looks lifeless or dull in spots, you should ask specifically about the proportioning of the cut. In addition, you should ask if there are any cutting faults that might make the diamond more vulnerable to shipping or breaking, as for example, an extremely thin girdle would.
Has this diamond been clarity enhanced?

Be sure to ask whether or not the diamond has been laser treated, or fracture filled. If it is accompanied by a GIA diamond report, the report will indicate lasering, if present. However, GIA won't issue a report on a fracture filled diamond and some jewelers don't know how to detect them. If there is no GIA diamond report, be sure to ask explicitly, and get a statement in writing that the diamond is or is not clarity enhanced, whichever the case may be. Getting this fact in writing may save you a big headache should you learn later that the diamond is enhanced.
Does this diamond show any fluorescence?

If a diamond fluoresces blue when viewed in daylight or under daylight type fluorescent light, it will appear whiter than it really is. This can be desirable quality so long as the diamond has not been graded or classified incorrectly. A diamond may also fluoresce yellow, which means that in certain light its color could appear worse than it actually is. If the diamond has a diamond grading report, any fluorescence will be indicated there. If there is no report, and if the jeweler can't tell you whether or not the diamond exhibits fluorescence, the diamond's color grade may be incorrect.

Special tips when buying a diamond

Ask the jeweler to clean the diamond

Don't hesitate to ask to have the diamond cleaned before you examine it. Cleaning will remove dirt, grease, or indelible purple ink. Cleaning is best done by steaming or in an ultrasonic cleaner. Cleaning also helps to ensure that you'll see the full beauty of the diamond; diamond can become very dirty just from customers handling them, and, as a result, look less brilliant and sparkling than they really are.

View the diamond against a dead white background

When looking at unmounted diamonds, look at them only against a dead-white background such as white blotter paper or a white business card, or on a grading trough. Examine the stone against the white background so that you are looking at it through the side, not down through the table. Tilt the diamond toward a good light source; daylight fluorescent lamp is the best. If the diamond shows any yellow body tint when viewed through the girdle, if it is not as colorless as an ice cube, then the diamond is not "white" or "colorless."

Get the facts on a bill of sale

Ask that all the facts concerning the diamond be put on the bill of sale. These include the carat weight, the color and flaw grades, the cut, and the dimensions. Also, be sure you obtain the report on any "certificated" diamond, as diamonds accompanied by laboratory reports are sometimes called.

Verify facts a with a gemologist

If a diamond is one carat or larger and not accompanied by a respected laboratory report, make the sale contingent on verification of facts by a qualified gemologist, gem testing lab, or the GIA. While the GIA will not estimate dollar value, it will verify color, flaw, grade, make, fluorescence, weight, and other physical characteristics.

Weight the facts

Decide what is important to you and then weigh the facts. Most people think color and make are the most important considerations when buying a diamond, but if you want a larger diamond, you may have to come down several grades in color, or choose a slightly spread stone, or select one of the new shapes that look much larger than traditional cuts. The most important thing is to know what you are getting, and get what you pay for.

What to ask when buying a colored gemstone

As with diamonds, it's very important to ask the right questions to help you understand the differences in gems you may be considering. Asking the following questions should help you to gain a greater understanding of the differences, determine what's right for you, and have greater confidence in your decision.

1. Is this a genuine, natural gemstone, or a synthetic?

Synthetic stones are genuine, but not natural.

2. Is the color natural?

Most colored gemstones are routinely color enhanced. However, gemstones such as lapis should not be, and you must protect yourself from buying dyed material that will not retain its color permanently.

Be especially cautious when buying any blue sapphire; make sure you ask whether or not the gemstone has been checked for diffusion treatment. Today, with diffused sapphire being found mixed in parcels of natural sapphires and unknowingly set into jewelry, it's possible that one may be sold inadvertently.

3. Clarify what the name means.

Be particularly careful of misleading names. when a gemstone is described with any qualifier such as Rio Topaz (which is not topaz), ask specifically whether or not the gemstone is genuine. Ask why the qualifier is being used.

4. Is the clarity acceptable, or do too many inclusions detract from the beauty of the gemstone?

Are there any flaws, inclusions, or natural characteristics in this stone that might make it more vulnerable to breakage with normal wear? This is a particularly important question when considering a colored gemstone.
While visible inclusions are more common in colored gems than in diamonds, and their existence has much less impact on value than they have on diamond value, value is nonetheless reduced if the inclusions or blemishes affect the gemstone's durability, or are so numerous that they mar its beauty.
Be especially careful to ask whether or not any inclusion breaks the stone's surface, since this may weaken the gemstone, particularly if the imperfection is in a position normally exposed to wear, like the top of the stone or around the girdle. This would reduce the gemstone's value significantly. On the other hand, if the flaw is in a less vulnerable spot, where it can be protected by the setting, it may be of minimal risk and have little effect on value.

A larger number of inclusions will usually detract noticeably from the beauty, especially in terms of liveliness, and will also generally weaken the gemstone and make it more susceptible to any below or knock. Such gemstones should be avoided unless the price is right and you're willing to assume the risk.

Also, certain gems, as mentioned previously, are more brittle than others, and may break or chip more easily, even without flaws. These gemstones include opal, zircon, and some of the new and increasing ly popular gems, such as iolte (water sapphire) and tanzanite. This does not mean you should avoid buying them, but it does mean you should give thought to how they will be worn and how they will be set. Rings and bracelets are particularly vulnerable, since they are more susceptible to blows or knocks; brooches, pendants, and earrings are less vulnerable.

5. Do you like the color? How close is the color to its pure spectral shade? Is it too light? Too dark? How does the color look in different types of lights?

Learn to look at color critically. Become familiar with the rarest, and most valuable, color of the gem of your choice. But after you do this, decide what you really like, for yourself. You may prefer a color that might be less rare, and therefore more affordable. Be sure the color pleases you; don't buy what you think you should buy unless you really like it.

6. Is the color permanent?

This question should be asked in light of new treatments (such as diffusion) and also because color in some gemstones is prone to fading. two examples are amethyst and kunzite (one of the new and increasingly popular gems). Just which ones will fade and which won't, and how long the process might take, no one can know. This phenomenon has never affected the popularity of amethyst and we see no reason for it to affect kunzite's popularity, but we feel the consumer should be aware of it. There is evidence that too much exposure to strong sunlight or intense heat contributes to fading in these gemstones, so we suggest avoiding sun and heat. It may be wise to wear these gems primarily for "evening" or "indoor" activities.

7. Does the gemstone need protective setting?

The setting may be of special importance when considering gemstone like tanzanite, opal, or emerald. They require a setting that will offer some protection; for example, one in which the main stone is surrounded by diamonds. A design in which the gemstone is unusually exposed, such as in a high setting or one with open, unprotected sides, would be undesirable.

8. Does the gemstone have a pleasing shape? Does it have a nice "personality?"

This will be determined by the cutting. Many colored gems are cut in fancy shapes, often by custom cutters. Fine cutting can enrich the color and personality, and increase the cost. However, with colored gems brilliance and sparkle are less important than the color itself. The most critical considerations must focus on color, first and foremost. Sometimes a cutter must sacrifice brilliance in order to obtain the finest possible color. But if the color is not rich enough or captivating enough to compensate for less brilliance, ask if the jeweler has something that is cut better and exhibits a little more sparkle. Keep in mind, however, that the more brilliant gemstone may not have the precise color you like, and that when buying a colored gem, color is the most crucial factor. Unless you find the gemstone's personality unappealing, don't sacrifice a beautiful color for a stone with less appealing color just because it may sparkle more. Compare, decide based upon what you like, and what you can afford.
When considering a pastel colored gem, remember that if it is cut too shallow (flat), it can lose its appeal quickly (but only temporarily) with a slight build up of greasy dirt on the back; the color will fade and liveliness practically disappear. This can be immediately remedied by a good cleaning.

9. What are the colorless gemstones?

In a piece of jewelry where a colored gemstone is mounted with colorless stones to accentuate or highlight its color, ask, "what are the colorless stones?" Do not assume they are diamonds. They may be diamonds, zircons, man-made diamond imitations such as CZ or YAG, or synthetic white spinel (spinel is frequently used in the Orient).

Special tips to remember when buying a colored gemstone

- When looking at unmounted gemstones, view them through the side as well as from the top. Also, turn upside down on a flat white surface so they are resting on the table facet and you can look straight down through the stone on the table facet and you can look straight down through the stone from the back. Look for evenness of color versus color zoning; shades of lighter or darker tones creating streaks or planes of differing color.

- Remember that color is the most important consideration. If the color is fine, the presence of flaws or inclusions doesn't detract from the gemstone's value as significantly as with diamonds. If the overall color or beauty deter is not seriously affected, the presence of flaws should not deter a purchase. But, conversely, flawless gemstones may bring a disproportionately higher price per carat due to their rarity, an larger sizes will also command higher prices. In pastel colored gems, or gemstones with less fine color, clarity may be more important.

- Be sure to check the gemstone's color in several different types of light; a spotlight, sunlight, or fluorescent or lamplight, before making any decision. Many gemstones change color; some just slightly, others dramatically, depending upon the light in which they are viewed. Be sure that the gemstone is a pleasing color in the type of light in which you expect to be wearing it most.

If considering a gemstone with rich, deep color; especially if it is for special occasions and likely to be worn mostly at night, be sure it doesn't turn black in evening light.

- Remember to give special attention to wear-ability. If you are considering one of the more fragile gemstones, think about how the piece will be worn, where, and how frequently. Also, pay special attention to the setting and whether the gemstone is mounted in a way that will add protection, or allow unnecessary, risky exposure to hazards.

Get the facts on the the bill of sale

If a colored gemstone is over one carat and exceptionally fine and expensive, make the sale contingent on verification of the facts by a qualified gemologist, appraiser, or gem testing lab such as GIA or American Gemological Laboratory (AGL).

Always make sure that any item you purchase is clearly described in the bill of sale exactly as represented to you by the salesperson or jeweler. For diamonds, be sure each of the 4 Cs is described in writing. For colored gems, essential information also includes the following:

- The identity of the stone or stones and whether or not they are genuine or synthetic, and not in any way a composite (Doublet, triplet).

- A statement that the color is natural, if it has been so represented; or, in the case of sapphire, a statement that the stone either is surface diffused, or that it is not surface diffused.

- A statement describing the overall color (hue, tone, intensity).

- A statement describing the overall flaw picture. This is not always necessary with colored gemstones. In the case of a flawless or nearly flawless gemstone it is wise to note the excellent clarity. In addition, note any unusual flaw that might prove useful for for identification.

- A statement describing the cut or make. This is not always necessary, but may be useful if the gemstone specially well cut, or an unusual or fancy cut.

- The carat weight of the main gemstone or gemstones plus total weight if there is a combination of main and smaller gemstones.

- If the gemstone is to be taken on approval, make sure that the exact dimensions of the gemstone are included, as well as any other identification characteristics. The terms and period of approval should also be clearly stated.

Other information that should be included for jewelry

- If the piece is being represented as being made by a famous designer or house (Van Cleef and Arpels, Tiffany, Caldwell, Cartier, etc.) and the price reflects this, the name of the designer or jewelry firm should be stated on the bill of sale.

- If the piece is represented as antique (technically, an antique must be at least a hundred years old) or as a "period" piece from a popular, collectible period like Art Deco, Art Nouveau, Edwardian (especially if made by a premier artisan of the period), this information should be stated on the bill of sale, with the approximate age or date of manufacture, and a statement describing "condition."

- If made by hand, or custom designed, this should be indicated on the bill of sale.

- If the piece is to be taken on approval, make sure millimeter dimensions; top to bottom, as well as a full description of the piece. Also, check that a time period is indicated, such as "two days," and before you sign anything, be sure that you are signing an approval form and not a binding contract for its purchase.

Tuesday, June 29, 2010

Gemstone Treatments And Disclosure

By Derek Parnell

When you purchase your next gemstone be sure to ask if the gemstone has had any treatments, as this can affect the value and durability of the gemstone. A good jeweller will automatically make this disclosure as part of the sale.

If you are purchasing a high-value gemstone such as Ruby, Emerald or Sapphire make sure it has a certificate from a laboratory that has the expensive equipment required to be able to detect some of these treatment. Most jewellers and gemologists have equipment that can detect certain levels of treatment, but it is only the laboratory equipped grading companies such as Gemological Institute of America and European Gemological Laboratory that can detect all the treatments available.

There are 10 major gem treatments that require disclosure from the seller to the buyer.

Bleaching, Cavity Filling, Colorless Impregnation, Dying, Fracture Filling, Heat Treatment, Irradiation, Sugar & Smoke Treatment, Surface Diffusion, Surface Modifiers. In this article we will look at 5 of them.

Cavity filling This type of treatment refers to those gemstones that have defects on the surface of the gemstone; these cavities and surface reaching fractures reduce the appearance and value of the gemstone. To enhance the value these imperfections are filled with different resins, plastic or glass, which improves the appearance and increases the gemstone weight. Due to the different Reflective Index of the filler material most gemologist can detect the fillers.

Dying. Is used to enhance the color of gemstones such as Chalcedony, Lapis, Jadeite, Cultured Pearl and Turquoise. These gemstones have one thing in common they are all porous, which enables the dye to reach just below the surface. To assist in having the dye penetrate, some gemstones are heated and then cooled quickly by quenching in water, this causes minute surface cracks into which the dye will flow. The more color a gemstone has the more appealing to the consumers.

Heat Treatment This is the most common among treatments and is used extensively on corundum (Sapphire, Ruby) to enhance the color of the gemstone. Heat can also be used to remove internal blemishes, or color centres to improve the gemstones color consistency. Most gemstones that are heated result in enhancing or changing the color are stable, however they are still enhancement and should be disclosed.

Irradiation You will find this treatment in some colored gemstones and colored Diamonds. This process began in the early 1990s and is used widely today, there are minimal traces of radiation in the gemstone but its never harmful if the correct procedures have been followed. The challenge in gemstones is the lack of stability and its sensitivity to heat once the process has been completed. Therefore it is important that you know the gemstone has been irradiated, if you ever have a jewellery item repaired make sure the stone is removed, as the heat will change the color. Most colored Diamonds are made affordable by irradiating the natural browns and yellow, which can turn them into blue, green and red colors making them more attractive and increasing their value. The process in diamonds is more stable but is still susceptible to changes with heat.

Surface Diffusion This treatment is becoming more common today with the enhancement of more valuable gemstones such as corundum. The gemstone is heated just below melting point, and then chemicals are used to penetrate the surface to become part of the crystal structure. This process is also used to produce stars (asterism) in some gemstones, again increasing value.

Disclosure It is not only unethical, it is also against the law to sell a natural gemstone that has been treated and not disclose the treatment. If a jeweller or gemologist does not know if a gemstone has had a treatment then he should assume it has and disclose it, or send to a laboratory to confirm one way or another. All treatments must be disclosed at the time of sale to the consumer. Unfortunately, today there are a lot of treated gemstones being sold as natural.

The reason sellers fail to disclose falls into four main categories:

Ignorance, they believe their suppliers, who mostly live in countries where these rules are not adhered to or do not exist.

Competitive Pressure, they feel they will be disadvantaged in a sale if their competitors do not disclose.

Resistance, they do not believe in the rules and do what they think is right.

Calculated Risk, If they don't disclose how often will they get caught and if they are caught they can probably make the problem go away by refunding or replacing the item.

A reputable seller will always provide disclosure, but its not a perfect world.


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Looking After Gemstone Jewellery

By Tim Vogel
Caring For Your Gemstone Jewellery:

Precious and semi-precious gemstone species, commonly used in jewellery, vary greatly in their intrinsic 'hardness'. In general, most gemstones have come to be favoured for adornment not only as a result of their inherent visual attractiveness, but also because they belong to a particular species, which is hard enough to withstand the vigour's of daily wear.

However, with the possible exception of diamond, all gemstones are susceptible to damage. Almost all will suffer scratches and chips in contact with most metals and all can be damaged by extremes of temperature and pressure. A few semi-precious gemstones are extremely soft and can be damaged by a fingernail!

In fact, it's even a fallacy to say that diamond cannot be damaged -diamonds will shatter in some circumstances. The old 'glass test',beloved of thriller writers, by which one tests the quality/authenticity of diamond jewellery, by attempting to scratch other hard surfaces, is not recommended!

As there are large differences in 'hardness' and therefore resilience to scratches, knocks, bumps and bangs, between each gemstone species, it's sensible to apply the same care considerations to all, before then applying additional specific special care for your particular gemstone species.

Cleaning Gemstone Jewellery.

· Keep your gemstone jewellery clean. A dry soft cotton cloth rub, after each wear, is by far the best way to prolong the beauty of your jewellery.

· Harder non-porous semi-precious gemstones, such as the quartz family and most precious gemstones can have heavy dirt removed using mild soapy water and a damp cloth. However several semi-precious species are not only porous but actually DISSOLVE in water! Great care is needed in accurately identifying your gemstone.

· It is wise to protect all semi-precious and precious gemstones from excessive heat and pressures. Both when wearing and when in storage.

· Excessive sun exposure will affect most semi-precious gemstones, some such as Amethyst will actually change colour.

· Household chemicals, cosmetics, body oils and dust can all damage gemstones. Always put your jewellery on after your make-up and perfume.

· Do not use silver cleaner on gemstones. Be careful to ensure that the silver cleaner only touches the silver part of your jewellery. Anti-tarnish agents can damage some gemstones.

· Store gemstone jewellery pieces individually - do not store in a big jumbled jewellery box. Your gemstone jewellery will scratch in contact with other jewellery items.

· Turquoise, Opals, Pearls, Mother of Pearl, Abalone, Shells and Corals all benefit from breathable storage. These species do not like long exposure to dry heated environments.

· It is sometimes advised to occasionally immerse gemstones, such as Opals, in water. Opals need moisture to look at their best. However, as most jewellery is a combination of materials, we would not advise immersion of your jewellery. It's also important to note that water is very rarely free of microscopic particulate matter, such as salts and other minerals; once the moisture has dried these particles remain trapped inside the gemstone. One has only to look at a granite cliff-face, to see the natural repercussions of this geological process. Cracks and fissures will form within your gemstone in exactly the same way!

· Strung beads and gemstone necklaces will hold onto moisture within the stringing material and should never be immersed in water.

If in any doubt, it is always best to seek the professional cleaning service of a jeweller. The cost of professionally cleaning your precious jewellery is not likely to be very great, especially when considered in relation to the 'cost' of damaging your jewellery.In the case of precious gemstone jewellery, the stone itself is likely to be by far the most expensive and difficult component to replace, regularly check the prongs, clasps and fitments of your jewellery.


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