Gemstones

PROTECT YOUR GEMSTONES

-Remove all jewelry before engaging in such activities as sports, housework or yard work where jewelry is prone to impacts and/or chemicals.

-Never remove jewelry by pulling on the gemstone. Pulling the stone exposes it to perspiration, skin oil and dirt, as well as the possibility it will become loose in its setting.

-Check for loose gems and clasps before each wear.

-Have a jeweler restring your pearl and bead necklaces at least every two years, annually if you wear them frequently.

-Never store jewelry in piles to avoid gems and metals abrading each other or chains entangling. Wrap each piece in velvet, paper or silk; or separate in sections of a jewelry box or fabric pouch.

Rock Solid

One of the biggest factors to consider in the care of precious gems and metals is their hardness, which reflects their durability. To measure hardness, the jewelry industry uses the Mohs Scale. This gem-trade standard, conceived by Friedrich Mohs in the early 1800s, measures the ability of a gem or mineral to resist abrasion damage. Diamond is placed as the hardest substance at 10, while talc is considered the softest at 1. Rubies and sapphires rate at 9, topaz and spinel at 8 and quartz material (such as amethyst and citrine) at 7.

Most of the objects you and your jewelry come in contact with are either quartz-based or near quartz's hardness. If your gems are harder than Mohs 7, they will not be scratched; if they are softer, they could get damaged. And, believe it or not, the precious metals your gems are set in (platinum, gold and silver) fall below Mohs 4.5. 

Rings and bracelets are most vulnerable to the realities of daily wear. But earrings and necklaces, even brooches, are also subject to chemical exposure, particularly if worn while cosmetics, perfume and hairspray are applied. 

In addition to regarding how you wear and store your gemstone jewelry, you should consider how you clean it. Choose chemicals, brushes and techniques for the softest, most vulnerable gems in a piece. Although the precious metals used in jewelry are softer than most gems, it does not mean that cleaners tailored to a specific metal will not damage gems of a higher Mohs. For example, silver polish works fine for sterling alone, but can ruin porous gems (like opal, pearl, coral, lapis, turquoise, and amber) set in it. Ammonia is a particular threat to fragile gems. If you must use strong commercial products, and you can't bear to remove that ring, make sure you are wearing protective gloves (which you should do anyway, to protect your skin!). 

The best way to clean most of your gem-set jewelry is to use a mild soapy solution in warm water, a soft brush, and a soft cloth to pat dry.

THE BASICS 

As with diamonds, gemstone quality and value are evaluated according to the "Four Cs": color, clarity, cut, and carat weight. And there's one other, much less scientific factor--perception. 

Color, not surprisingly, is the key factor. A common misperception in judging gems is people assume that the darker the color, the better the stone. That isn't true: color can be too dark, as with some sapphires that look more black than blue. If a gem's color is too dark, it is subdued and lifeless. A much better rule of thumb is the brighter and more rich and vivid the color the better. In general, within each gemstone variety, a clear, medium-tone, very intense and saturated basic color is the most preferred. Muted colors or colors between hues, which some might find very attractive, are usually less expensive. Look at the color in different kinds of light, since the light spectrum can affect color greatly.

The next most important factor affecting value is clarity, with clear transparent gemstones with no visible flaws being the most valued. Some gemstone varieties, notably emerald and red tourmaline, are very rare without inclusions of some kind so the price structure takes this into account. Other gems are actually valued for their inclusions! Tiny inclusions reflecting back light put the eye in cat's-eye chrysoberyl and the star in star sapphire and ruby. Inclusions can also act as a birthmark, telling where a particular gemstone was mined. 

A good cut is something that may not cost more but can add or subtract a lot of beauty. A well-cut faceted gemstone reflects light back evenly across its surface area when held face up. If the stone is too deep and narrow, areas will be dark. If it is too shallow and wide, parts of the stone will be washed out and lifeless.

Gemstones are generally sold by weight not by size. Some gems are denser than others so the same weight stone may be a different size! The carat weight also affects the price--large gemstones are usually more rare, so the price per carat is higher.

GEMSTONE QUALITY

When buying diamond jewelry, adhere to the Four Cs of diamond quality. Be especially mindful of cut and color. 

When you look at the stone, it should have an even brilliance, with no parts looking shadowed or dark. Experts warn that improperly cut diamonds, especially pear, oval and marquise shapes, can give a viewer an undesired "bow-tie" shadow effect when looking at it. 

Also on the matter of cut, be sure the facets are of an even and symmetrical size and well-polished. The outline of the stone must be even and well-defined. 

In terms of color, unless you are buying a fancy colored diamond, you'll want your stone to be as close to totally colorless as possible. It's that colorlessness that gives the stone the most reflective and refractive properties--in other words, what gives a diamond its sparkle.

COLOR

When buying a ruby, sapphire, emerald or any other colored gemstone, look for rich color, translucency and brilliance. Don't make the mistake of thinking a very dark-colored stone is more valuable than a lighter one. Your best rule of thumb is to look for vibrant color rather than deep color.

Just as clarity is important in a diamond, transparency and translucency are essential in colored gemstones. Because they are formed in nature, most gemstones do have some inclusions but many are invisible to the naked eye. Some gems, such as emeralds, tourmalines, peridots and rubellites, have more inclusions than other stones, but this is not always considered a negative factor if their color is strong

STYLING

When buying a piece of gemstone jewelry, let your eye be the judge. Look for harmony and balance. For example, in a gemstone ring the stone and the ring shank should be in proportion. To have a very large stone balanced on a thin ring would look silly. Likewise, a very thick band and heavy setting for a small stone is not desirable. 

In fact, many of the best-designed pieces of jewelry use several different sizes and shapes of stones and different setting techniques to achieve a unique look. For example, an engagement ring may have a round, brilliant center stone held in place with six prongs, widely known as a "Tiffany" setting. The center stone might be bordered on two sides by rows of diamond baguettes (long, rectangular cut diamonds) in a channel setting, where the stones touch each other at the sides and are held in place by two railroad tracks of metal. Or, the center stone could be raised above a surface covered with tiny diamonds, known as diamond pave.

DETAIL 

With a prong setting, be sure the prongs are balanced evenly around the stone and hold the stone securely. If stones are set in a bezel--a sort of gold picture frame of metal around the stone--be sure the bezel is straight and uniform and the stone is not moving within the setting. 

In channel or invisible settings, where many stones are set tightly together with no metal showing, the stones should all be the exact size, shape and color. The facets should all line up and no one stone should be more prominent than another. 

In pave, where tiny stones are set into a gold surface and the gold is pushed up around each stone using a hand-held tool, you should see nothing but a sparkling surface of diamonds. If the surface is uneven, or one stone is higher or lower than the ones around it, it's not good workmanship. Most times, white diamonds will be pave set in platinum or white gold, but pave can be done in yellow or pink gold as well. 

Finally, to judge the quality of any piece of jewelry, turn it over. The back (or inside of a ring) should be just as beautiful as the front, polished and beveled nicely, not rough and unfinished-looking. If you have a piece with several stones set closely together, the metal should be cut away in square or honeycomb patterns at the back, (known as gallery work), allowing the maximum amount of light to shine through.

GEMSTONE CLEANING

Alexandrite (Mohs 8.5) Clean with soapy water, alcohol or commercial cleaning solutions. An ultrasonic cleaner or steamer is safe.

Amber (Mohs 2-2.5) Use only warm soapy water, no brush. Pat dry. Do not use mechanical cleaners; avoid abrasives, chemicals and heat.

Aquamarine (Mohs 7.5-8) Warm soapy water and a soft brush is your best bet. Mechanical cleaners are safe, but not on heavily included gems. Avoid most chemicals, heat and excessive cleaning.

Coral (Mohs 3.5-4) Gently wipe clean with a soft, cool, damp cloth. Do not use a brush or mechanical cleaners. Avoid abrasives, chemicals and heat.

Diamond (Mohs 10) Mechanical cleaners are safe, unless a stone has fractures or is fracture-filled. If that is the case, avoid heat and chemicals. Ammonia-based cleaners or mild solvents are fine. If using warm soapy water, rinse well and pat dry to avoid residue. Vodka is said to produce sparkling results.

Emerald (Mohs 7.5-8) Clean with a soft, damp cloth, warm water and a soft brush. Do not use mechanical cleaners. Avoid chemicals and heat that dissolve oils used during cutting and processing to conceal inclusions. Although emerald is harder than quartz, its crystal structure makes it brittle. Have a jeweler re-oil your emerald every few years. Avoid impacts.

Garnet (Mohs 7-7.5) Warm soapy water and a soft brush is perfect. An ultrasonic cleaner is safe for most garnets, except andradite (the best known variety is demantoid). Do not use a steamer.

Jade (Mohs 6.5-7) Warm soapy water will do the trick. Mechanical cleaners are safe. Avoid contact with warm acids.

Lapis Lazuli (Mohs 5-6) Use warm soapy water. Do not scrub or soak. Wipe with a soft cloth. Do not use mechanical cleaners and avoid chemicals.

Opal (Mohs 5-6.5) Use a soft dry or damp cloth. Do not soak. Do not use mechanical cleaners. Avoid impacts, dry conditions, heat and chemicals.

Pearls (Mohs 2.5-4.5) Wipe clean after each use with a soft, dry or damp cloth. Mild soapy water is fine. No mechanical cleaners, heat or chemicals.

Peridot (Mohs 6.5-7) Warm soapy water and a soft brush is your best bet. Do not use an ultrasonic cleaner or steamer. Avoid contact with acids.

Quartz (amethyst, citrine & ametrine) (Mohs 7) Warm soapy water is perfect. An ultrasonic cleaner is usually safe, but a steamer is risky. Avoid acids, intense heat, and prolonged bright light.

Ruby & Sapphire (Mohs 9) Clean with soapy water or commercial solvent and brush. Mechanical cleaners are safe, except for heavily included gems.

Spinel (Mohs 8) Give it the kind of care you would ruby and sapphire.

Tanzanite (Mohs 6-7) Give it the same kind of care you would a peridot.

Topaz (Mohs 8) Give it the same care you would an emerald. Although it is hard, it cleaves. A sudden temperature change or impact can cause a break.

Tourmaline (Mohs 7-7.5) Warm soapy water and a soft brush is your best bet. Do not use mechanical cleaners.

Turquoise (Mohs 5-6) Wipe with a soft damp cloth and dry. Do not soak or use mechanical cleaners. Avoid chemicals. Silver cleaners will cause discoloration.