Gems, Stones, and Metals

Learn About Fine-Colored Gems

It is reasonable to expect lasting value and enjoyment when you purchase gemstone jewelry. Learning a few things about gemstone quality and value will help you make sure you get what you want and deserve.

Start by trusting your instincts. That immediate first impression can be very powerful and also right. If a particular gem or jewelry design really “speaks” to you, you should listen.

Every different gem variety is judged by its own potential and particular characteristics. There are however, a few general rules you can use to judge gemstone quality.

Color

Every gem has a unique range of colors. The purest and most vivid color a gem can have will also be the most expensive. To really explain gem color, we need to look at the three factors that define any color – Hue, Saturation & Tone.

Hue – Hue is what we normally regard simply as color: red, orange, yellow, green, blue or purple or in between two hues: orangey red or reddish orange. For most gem varieties, a pure hue is most favored.

Saturation – The second factor, Saturation is the intensity of the color. Colors that lack intensity often appear faded or washed out or look as though the hue is mixed with gray or brown. A fire engine red is highly saturated, a brick red less so. In gemstone color more saturation is always better.

Tone – Tone is the lightness or darkness of the color. Pink has a light tone and maroon has a dark tone. In gems, a medium tone, not too light but not too dark, is considered the best. Too light and a gem’s color is too pale to be attractive. Too dark and a gem isn’t able to sparkle with light.

Cut

Next to color, cut is the most important factor in beauty. Faceted gemstones in particular should have a pleasing shape with a lively display of color and light. The flashes of brilliance a beautiful faceted gem displays are thanks to the skill of the cutter, who selects just the right orientation and angles and proportions to maximize a gemstone’s appeal.

Well cut faceted gemstones display brilliance and scintillation evenly across the face of the gem. Unlike diamonds there is no “ideal” set of proportions for cut in a colored gem. Each variety is different optically and requires different angles and ratios to look its best.

As you look at the gem move it around and see how it handles light. There should not be any dark lifeless areas or flat washed out zones. Light should be reflected consistently back to the eye. Poorly cut gems may have a windoe; a non-sparkling area in the center where light just shines through the back of the gem instead of being reflected back to dazzle you eye.

Faceted colored gemstone come in many traditional shapes-ovals, rounds, cushions, trillions, emerald cuts, princess cuts, pear shapes and marquis shapes and many newer fancy and designer cuts.

Other colored stones are judged by their depth of color and play of color. Gemstones such as opals, chalcedony, cat’s-eyes, star sapphires, coral, turquoise and other rich colored gems are often cut in a smooth dome shape called a cabochon. This cut emphasizes color over brilliance.

Today the work of many innovative lapidary artists and talented cutters adds unique possibilities in designer gemstones. Faceting new shapes and styles or carving beautiful sculptures in gem material provide unlimited possibilities for one of a kind jewelry.

Clarity

All natural gemstone have characteristic inclusions that form along with the gem in the earth. These inclusions may be crystals, needles, voids, fissures, or even tiny pockets of liquid trapped inside. In most gemstones if they don’t detract from appearance, clarity features are accepted and don’t affect value. Often they are beneficial because they prove that the gem is natural.

The most valuable and sought after by collectors are those with no inclusions readily visible with the naked eye, particularly in gems of a light color. These gemstones can be very rare. Visible inclusions are common and expected in emerald, red tourmaline and to a lesser extent, ruby.

Carat Weight

Most colored gems are available in a wide range of sizes, but for some the selection is limited. Gems are generally sold by weight, using the carat, which is one-fifth of a gram. Some gem varieties are denser than others: a one carat emerald will be noticeably larger in size than a one-carat sapphire or ruby. In general, the larger the gem, the more expensive it will be per carat.

For the classic gems like ruby, emerald, and sapphire, prices per carat can increase dramatically as sizes increase. For example, since large ruby is very rare, a three-carat ruby might be three times the price per carat of a one-carat ruby, or nine times the total price.

Some gems are much more available in large sizes so the price doesn’t rise as much as the size goes up. Amethyst, Citrine, Aquamarine, Tanzanite, and Tourmaline might have similar prices per carat for a one-carat and a ten-carat stone.

Rarity

In addition to the 4Cs, gem values are influenced by natural rarity and the economics of supply and demand. This explains why gems that look similar in color and size can differ substantially in price.

Both sides of the equation of supply and demand come into play. Alexandrite, rare but in demand from collectors, may cost as much as better-known gems. Some gems are relatively rare but since they aren’t well known, there is little demand, keeping prices low. The ancient world couldn’t tell ruby and spinel apart, but spinel’s role as an unknown understudy keeps its price relatively low today even though a one-carat red spinel is more rare than a one-carat ruby. Other rare gems that are relatively affordable include tsavorite garnet, morganite, red beryl, and zircon.

Within each gem variety, quality determines cost. But different gem varieties have different pricing structures. In general, classic ruby, blue sapphire, and emerald are the most expensive gemstones. One level below these are the rare collector’s gems like alexandrite, demantoid garnet, Paraiba tourmaline, black opal, pink topaz, jadeite, chrysoberyl cat’s eye, fancy sapphire and South Sea cultured pearls. The moderate price range includes tanzanite, tsavorite garnet, tourmaline, red spinel, aquamarine, precious topaz, spessartite garnet, and Tahitian cultured pearls. Affordable gemstones include amethyst, citrine, spinel, many colors of garnet, blue topaz, chrome diopside, fire opal, white opal, iolite, kuzite, peridot, coral, turquoise, lapis lazuli, chalcedony, and freshwater and saltwater cultured pearls.

The Perfect Setting

The creativity and craftsmanship that go into fashioning gems and making jewelry also affects the value of the finished piece. Beautiful and exquisite gems reflect the union of aesthetics, science, and technical mastery. Fine jewelry combine gems and precious metal with talented design, skilled execution and attention to the smallest details. Many of today’s unique cuts and gemstone sculptures require a jewelry designer willing to work with these unusual materials.

It makes sense to have the guidance of a professional you trust when you purchase your colored gemstones and jewelry.

Christopher’s Fine Jewelry Design is a member of the American Gem Trade Association. Lois Wacholtz, the co-owner of Christopher’s serves on the Board of Directors. Members of the AGTA are gemstone professionals. We carry a large selection of loose gemstones and have relationships with many highly reputable gem cutters and dealers. We have specialized knowledge and training and will provide you good advice about choosing gems and jewelry. We will include full disclosure of all the facts that are needed to make an educated and satisfying purchase decision.

We are passionate about gemstones and jewelry and want to share the beauty and wonder of natural colored gemstones and cultured pearls.

To learn more about individual gemstones and to see the individual loose gems and to meet the cutter, reserve a seat for yourself and your friends at our Gemstone Roundtables. To meet with our senior jewelry designer, Christopher M. Jupp, request an appointment. Consultations are free.

Note: This information is adapted from the American Gem Trade Association

Gemstones and Rough Material

Definitions

Color

When judging gemstones, color is a term that encompasses three qualities: hue, saturation and masking. Each quality is important, and affects the overall look of the gem.

Hue is the main body color of the gem, such as purple amethyst or green tourmaline.

Saturation is the strength or purity of the hue. Aquamarines are usually lighter – less saturated – than garnets.

Masking is the lightness to darkness tone of the gem overall. Thai sapphires can be very dark, but the darkness is often due to a dark masking, not a saturated blue hue.

Precious/semi-precious gem

Precious and semi precious are old-fashioned terms that are slowly phasing out of the jewelry vocabulary. The term “precious” used to indicate ruby, sapphire and emerald, while the term “semi-precious” indicated every other type of colored gemstone.

Unfortunately a “precious” ruby can be worth $200 and a “semi-precious” tourmaline of the same size can be worth $5000. So the words start to lose their meaning when used in a real world scenario.

The term “colored gemstones” is the best description for all species of colored gems.

Carving

Carving a gemstone means to fashion it with concave surfaces, convex surfaces, flat planes, grooves, undercutting and relief, all of which create their own patterns of reflection. Carving may take the form of a fully three-dimensional sculpture or a more two dimensional intaglio/cameo.

Faceting

Faceting a gemstone means to fashion it with small flat planes. There is also concave faceting utilizing small curved planes.


Descriptions

Buying rough is an art form in itself. Learning to judge the quality of a crystal requires seeing inside the rough to the often hidden inclusions, judging the shape of the rough to discern the type of gem that might be carved, and understanding the cost/recovery equation.

Portfolio of rough

Rough, rough, rough, can you ever have enough?

Recovery in rough

Many people are shocked to hear that carving or faceting a gemstone requires a huge loss of rough. Thirty percent recovery is considered to be good. This means that seventy percent of the gem will be ground away in the cutting process. Fifteen percent recovery is considered to be low. This means that eighty-five percent of the gem was ground away in the cutting process. Whether you get high recovery or low recovery when cutting gem rough is an important issue for any working lapidary. Gem rough is expensive, and a bad judgment about expected recovery from an expensive crystal can be financially treacherous.

Treatments

Gems can be heated, irradiated, dyed, or altered in many different ways. If you are looking at one of Sherris’ gems, we will always tell you if it has been treated. Most of the gems that Sherris carves are not treated at all, but there are a few, such as aquamarine and tanzanite that are routinely heated to enhance the color.

Heating a gemstone generally involves burying it in sand or some other compound, putting it in a kiln and slowly raising the temperature until the desired color is reached. The gem is then allowed to cool slowly. There is no way to tell if a gem has been heated, and in most cases heating does not damage the gem structurally. Often heating is done at the mine, but lapidaries also heat single gems individually. Gems that are sometimes heated include aquamarine, citrine, amethyst, tanzanite, tourmaline and blue zircon. Ask your jeweler about the gemstones you are interested in. At Christopher’s we build close relationships with our gem dealers and cutters so that we can provide all the important information related to a particular gem. Our gemstone roundtables provide a wonderful opportunity for our clients to actually meet our gem dealers and learn about gems from the source.

Properties of gemstones

The physical and optical properties of gemstones affect their beauty, affordability, desirability and durability. We will be adding more information related to the following topics in the future.

  • Color and light
  • Weight and specific gravity
  • Hardness and toughness
  • Cleavage and fractures
  • Pleochroism

Information provided by Gemscapes. Thank you.

The Feldspars: Moonstone, Labradorite, Sunstone

Treatment & Enhancement

Moonstone, labradorite, and spectrolite have no known enhancements or treatments. Because moonstone is often very transparent, it is sometimes backed with a darker material during setting to show the phenomenal characteristics to their best advantage.

Origin

Moonstone is the most well-known member of the feldspar group, which includes labradorite, spectrolite, and sunstone. The largest moonstone deposits have been from India and Sri Lanka, but recently a deposit was found in Tanzania.

The primary characteristic of most fine feldspar is a beguiling play of light that shimmers playfully when the stone is moved, known as “adularescence”. The body color of moonstone can be clear, white, black, peach, yellow, beige, and grey. Sri Lankan moonstone is prized for its clear or white body color, but rich blue adularescence.

Labradorite, of course, is named for Labradore, Canada where it was discovered. However, most of the material today comes from Madagascar. Labradorite has a translucent greyish body color with an adularescence of greens, blues, violets, and golden hues.

Spectrolite is found primarily in Finland. Its body color is opaque with blue to green to violet flashes of adularescence.

The finest sunstone is found in Oregon, but fine specimens have recently been discovered in Tanzania. Both these localities produce clear body or semi-translucent body color with bright orange flashes. The Oregon material attributes its orange color to copper inclusions, whereas the Tanzanian material has microscopic hematite inclusions. India also produces sunstone, but it is opaque with hematite or goethite inclusions to give it the orange glitter. There is sunstone know as andesine which is diffused with copper, but it does not have the glitter of the sunstones described above.

Folklore

Ancient Romans believed moonstone was the magical crystallization of actual moonlight. The ancient Greeks called the moonstone Aphroselene, a combination of the names for the love goddess, Aphrodite, and the mood goddess, Selene. Thought to have magical powers it was used to treat all manner of physical illnesses and emotional problems. Moonstone was also a favorite of the French master goldsmith and designer, Rene Lalique and his contemporaries during the Art Nouveau period. Today in Arab cultures women often wear moonstones secretly sewn in their clothing as a symbol of fertility.

Care

With a hardness of 6 on the Mohs scale, moonstone is somewhat soft, but not brittle. All feldspar jewelry may be steam cleaned but should not be put in an ultrasonic.

Information supplied by Boston Gems. Thank You.

Opal Information

What Is Opal?

A very mysterious stone, for one. To me, opals are like windows by which one can see into the kingdom of heaven, and holding one is like having a little piece of heaven in the palm of your hand. Below are descriptions of the different kinds of opal and where they come from, as well as other bits of information.

Black Opal

The reason black opal got its name is because it came with a black body color or a natural black bottom under the color bar. This natural black backing to the opal gave it a rich, brilliant appearance. Lightning Ridge in New South Wales, Australia, is the main producer of black opal and occurs in small, nearly round balls or “knobbies”, looking very similar to footballs with the opal color bar going through the middle of the stone.

Because of the shape, most black opals are cut with a rounded bottom to preserve as much of the color on top as possible. Black is considered the rarest of all opals as it occurs rather sporadically or in small pockets usually between 30 and 60 feet underground. The natural backing of black opals runs from pitch black to grey. Generally speaking, the blacker the better, but it’s what’s up front that counts or really what’s on top that counts.

Boulder Opal

This unusual stone is usually sold by the piece, whereas almost all other opal is sold by carat weight. The reason is that the opal occurs in a host rock that is called boulder stone and is brown in color. This brown color has many different shades of brown and resembles wood with its many colors and patterns. There are several different types of Boulder Opal:

Boulder Opal – Solid opal on boulder stone
Boulder Matrix – Opal and boulder stone mixed together like the photo above. [NOTE: MISSING PHOTO] Ironstone Matrix – Boulder stone that has tiny dots of opal interspersed throughout the stone.

Koroit Boulder Opal

This is opal from an opal field called Koroit. Its unusual patterns intermixed with opal are what make it distinct from other types of Boulder Matrix. Much of the price is determined by artistry of the stone rather than the opal it contains, but higher quality opal will increase the price.

Without a doubt Koroit Boulder Opal produces the most incredible variety of opal. It is a real piece of art that God has created for our us to admire and cherish.

Rough Boulder Opal

This can occur in very small (often round) pieces or huge boulder stones weighing hundreds of pounds with veins of opal running through them. Most mining is done with excavators as the ground is usually fairly shallow from the surface to about 30 feet down.

Light Opal

This occurs mainly in the South Australian opal fields, Coober Pedy, Andamooka, Mintabie, and Lambena. It usually occurs in seams between 30 and 60 feet underground. Sold by the troy ounce, its attraction is the beautiful colors it produces from soft pastels to brilliant flashy crystal (opal color floating in a clear transparent base). In Coober Pedy, white is often the base color, whereas crystal is more prevalent in Mintabie and Andamooka but any of these fields produce a great variety of opal.

Black Opal Treated Matrix

This opal, from Andamooka, looks white just out of the ground, but one can see the opal color. The stone is then cooked in a sugar solution for 8 – 12 hours and then dried, after which it is cooked in a solution of sulfuric acid for about the same length of time. The opal is not affected by the treatment but is turns the base color of the stone to black and the opal color is outstanding on the black background.

This treatment gives the opal the appearance of natural black opal but under magnification you will see that it is a rather porous stone. Once you see black opal and treated matrix together you will start to see the difference right away.

Black Opal Doublets

This is a solid piece of opal that has been laminated to another stone, usually obsidian, or boulder stone. This utilizes opal that is to thin to be a solid, the dark background enhances the color and gives it the effect of natural black opal. Recently slicing machines have been used to slice thick opal into slices the thickness of a note card, thin! It makes for very flat doublets.

Most all of my doublets have a “cab” to them as it gives a nicer appearance and makes it easier for the stone to be set in a piece of jewelry.

Black Opal Triplets

Triplets are similar to doublets except that the opal is sliced wafer thin and then a clear quartz or glass top is put on the opal, so that there are three parts: The black backing, the slice of opal, and the clear top which gives the stone a rounded top or cabochon. Slicing machines were originally used to for making triplets. The slicing machine has a series of metal blades moving back and forth over the opal while grit is being sprayed on it.

It usually takes 8 hours to make a cut but the surface is so smooth it can be laminated to the backing material without lapping it flat. Most triplets are found in more inexpensive jewelry, but not always. To make a real gem triplet you still have to have gem-quality opal.

I hope this helps give you a better idea of the different types of opal there are, though I have only covered the Australian end to things. Opals have a personality all their own and no two are identical, very much like people. God created them to be seen, not to remain buried in the dirt. The miner’s quest is to find the opal, yours is to find the ones you love, and yes, there are many. – The Opal Man

Information provided by The Opal Man. Thank you.

Platinum

Platinum is pure, rare and naturally white. This makes it an ideal metal to set any gemstone whose color (or lack thereof) is it’s best and most important quality. This is especially true for setting diamonds as the natural white color of platinum casts no color into the diamond and enhances a diamond’s sparkle. Usually 95% pure, platinum never fades or tarnishes and it is hypoallergenic so perfect for sensitive skin.

Found in very few places around the world, platinum is 30 times more rare than gold (Platinum Guild). This not only makes it valuable but it holds its value. Platinum jewelry is very durable and resistant to wear. It is the most secure and protective metal to use for many lifetimes of wear and enjoyment. Platinum is a statement of individuality.

Platinum’s naturally white color never loses its brilliant luster. Compared to white gold, which is an alloy (mixture) using yellow gold, platinum maintains its white color. White gold is frequently plated with a rhodium plating to keep the bright white color that you expect. This plating can wear over time and needs to be redone to maintain its bright color.

Platinum is also more dense than gold. An identical ring made in platinum rather than 14 karat gold would be around 60% heavier and 40 % heavier than a ring made in 18 karat gold. (Platinum Guild)

When deciding which metal to have your next jewelry design done in consider the important positive facts about Platinum. It has and holds a high intrinsic value. It is durable and has a very long life span. It is one of the purest metals used. It is hypoallergenic. It has a comfortable heavy feel. And it is truly rare.

Consider making an appointment with Christopher today to design your one-of-a-kind platinum jewelry.