Terms used to describe optical effects in faceted and non-peeling gemstones
The physical characteristics of colored stones are often described in terms of how light passes through them, their unique visual effects and how they are cut. Here are some terms you need to know:
Transparent. The light passes easily through the stone, with minimal distortion, making it easy to see.
Translucent. The stone transmits light, but scatters it, forming an effect like frosted glass. If you try to read such a stone, the seal will be darkened and shaded.
Opaque. Does not pass light. You cannot see through it even on a tin frame.
Special optical effects
Adularescence. The swollen, moving, colored cloud effect observed in some gems, such as moonstones; and the inner, moving brilliance.
Asterism. Used to describe the manifestation of the star effect (four or six rays) when a stone is cut in a no-face style. Star ruby, garnet and sapphire.
Cat's eye. The effect created in some gems (when cut in cabochon style) is a thin, bright line across a stone that usually moves when the stone moves from side to side; sometimes called the cat's eye effect.
Multicolor. Rainbow color effect created by a thin film of air or liquid inside the stone. Most of the iris, observed in precious stones, is the result of cracks that destroy their surface. This diminishes the value, even if it looks beautiful.
Shine It usually reflects the surface of a gemstone and the degree to which it reflects light. It can be seen as glitter on the stone. A diamond, for example, has a much greater brilliance than amethyst. Pearls are also valued for their luster, but pearls have a softer, silky reflection than other gems. Glitter in pearls is often called a "guide."
The game of color. Often used to describe the fire observed in opal.
A cut
Colored gems can be cut or cut in a cabochon or without the grunge style. Generally speaking, the preference in the United States until recently was for faceted gemstones, so the final material was usually faceted. However, this has not always been the case in other eras and other countries; in Roman times, for example, it was considered vulgar to wear a faceted stone. Preference also varies according to different cultures and religions, and the best gems in the world are erased in both styles. Do not make any conclusions about the quality solely on the style of the slice.
Cabochon. Silent cutting style that creates smooth, not faceted surfaces. These cuts can be of almost any shape. some of them are round with high domes; others look like square-shaped domes (a popular kabochon with a sugar loaf); others are “buff-topped”, showing some kind of smoothed top.
Many people all over the world prefer the razor, often the more mysterious personality of the cabochon. Some connoisseurs believe that cabochons produce a richer color. In any case, today we are seeing much more interest and appreciation for cabochons around the world and more beautiful cabochons than we have seen on the market for many years.
Faceted. Cutting style, consisting in giving a stone many small faces at different angles to each other, as in various diamond cuts. The location, angle and shape of the faces or faces are carefully planned and executed to show the inherent beauty of the stone; fire, color, shine, to the fullest. Today there are many faceted styles, including a “fantasy” neckline that combines rounded surfaces with sculpted backs.
Importance of pruning
Cutting and dosing in colored stones are important for two main reasons:
They affect the depth of color observed in the stone.
They affect the vitality projected by the stone.
Color and cutting are the most important criteria when determining the beauty of a colored stone, after which the size of a carat must be taken into account; higher carat weights will usually increase the price per carat, usually in a non-linear proportion. If the colored gem was a good quality material to begin with, a good cut will fully enhance its natural beauty and allow it to manifest its beautiful color and vitality. If the same material is badly cut, its natural beauty will diminish, making it look dark, too light, or even "dead."
Therefore, when you explore a colored stone that looks bright in your opinion and has a good color; not too dark and too pale, you can assume that the cut is good enough. If the color of the gem is bad, or if it lacks animality, you should check i for the correct cut. If it was properly cut, you can assume that the core material was bad. However, if the incision is bad, the material can be very good and can be cut into a beautiful gem again. In his case, you may encounter a knowledgeable cutter to see if it is worth cutting, given the cost reduction and weight loss.
Estimate of the cut of colored stone
When studying the gem for the right cut, you should be guided by several considerations:
Is the shadow pleasant and the stone has life and brilliant?
If the answer is “yes” to both questions, then the basic material is probably good, and you should make a decision based on your personal preferences and budget.
Is the color too light or too dark?
If so, and the cut looks good, the main uncircumcised material is probably too light or too dark to begin. Consider a purchase only if you find the stone pleasant, and only if the price is right, that is, much lower than the gems of the best color.
Is the glossy shine even, or are there blind spots or flat areas?
Often the luster of a colored gem is not uniform. If the color is exceptional, a subdued sheen may not have a significant effect on its attractiveness, desirability, or value. However, the less beautiful the color, the more important the luster becomes.
the weight
Weight, like diamonds, weight in colored gems is measured in carats. All gems are weighed in carats, except for pearls and corals. These materials are sold in grains, moms and millimeters. Grain - 1/4 carat; mother - 18.75 carats.
As a rule, the greater the weight, the greater the value per carat, unless the gem reaches unusually large dimensions, for example, more than 50 carats. At this point, the size may become prohibitive for use in some types of jewelry (rings or earrings), the sale of such large gems may be difficult, and the price per carat may decrease. There are real trimmed topaz weighing from 2500 to 12 000 carats, which can be used as paper.
As with diamonds, do not confuse weight with size. Some gems weigh more than others; the density (specific weight) of the base material is heavier. A ruby is heavier than an emerald, therefore one carat ruby will have a different size than an equally formed and proportional emerald; ruby will be smaller in size, as it is heavier. An emerald weighs less than a diamond, so one carat emerald, cut in the same shape and with the same dispenser as the diamond, will be larger than the diamond because it is lighter and more weight is needed to achieve the same weight.
Some gems are easily available in large sizes; Tourmaline, for example, often occurs over 10 carats. For other gems, sizes larger than 5 carats can be very rare and are considered large and will also have a proportionately higher price. Examples include precious topaz, alexandrite, demantoid and tsavorite garnets, ruby and red beryl. With precious stones that are rare in large sizes, a stone of 10 carats can command at any cost.
The lack of a certain size among different colored gems makes the definition of “big” in the color gem market. Small 5-carat alexandrite or ruby - a very large stone; 18 carat tourmaline - “good size”.
As in the case of diamonds, gems under one carat sell less carats than stones over 1 carat, but here it becomes more complex. The definition of “large” or “rare” sizes is very different, as is the price, depending on the type of gemstone. for example, 8-carat tourmaline is a medium-sized stone, quite common and will be appropriately priced. A 5-carat tsavorite is extremely rare, and it will control the price proportionally much more than 1 carat. Precious topaz was easily available in sizes of 20 carats and more, but today even 10-carat stones of very thin color are practically absent, and their price has jumped sharply.
Gemstone Color Certificate
Systems for sorting colored gems are relatively new, and standards have not yet been established worldwide. As a result, certificates or sorting reports for colored gemstones are not widely used. Although diamond grading reports are widely used to describe and confirm diamond quality using precision, generally accepted standards, reports for colored gemstones have much more limited value. However, reports of colored gemstones are becoming much more important. Today's synthetics and other newly discovered gemstone materials create a need for reports that verify both identity (type of gemstone) and authenticity (whether or not they are synthesized). For any expensive colored gemstone today, especially gems of unusual size or exceptional quality and rarity, we recommend receiving a report from a recognized laboratory. The most widely recognized reports for colored gemstones include those released in the United States by American Gemological Laboratories, Inc. (AGL) and the GIA Gem Trading Lab; in Switzerland, the leading firms are the Gubelin Laboratory and the Schweizerische Stiftung fur Edelstein-Forschung (SSEF).
At the very least, color reports on gemstones should identify the gem and check whether it is natural or synthetic. You can also request a gradation report that will provide, in addition to your ID, a full description of the gem and an assessment of color, clarity, brilliance and other characteristics. This information is always useful for insurance purposes, and can also be useful if you are comparing several gems with a purchase target.
In cases where sufficient gemological data can be compiled after careful examination and with proper testing, some reports will also reveal whether a natural stone is or improved, or, if it is strengthened, in what way. Reports issued by the Gubelin laboratory, one of the most respected gem testing laboratories in the world, will not discriminate against the procedures as part of the policy. They believe that since most colored gemstones are usually processed in some way for centers, this is unimportant and that comparative qualities, beauty and rarity are important considerations. In addition, depending on the information, some laboratories will indicate the country of origin, if required. Laboratories Gubelin and AGL will indicate the origin where possible; GIA will not indicate country of origin.
The fee for color gemstone reports depends on the type of gemstone, the type of report requested and the time, skill, and gemology equipment needed to perform the final tests.
When considering a colored gem that is accompanied by a report, keep in mind the various types of reports available. Also keep in mind that the information presented in the report is as reliable as the gemologist who performs the assessment, so make sure that the report is issued by a reputable laboratory; If in doubt, consult one of the reputable laboratories to find out if they are familiar with the relevant laboratory. Then ask yourself what the message really tells you; Is this only proof of identity and authenticity? If so, remember that differences in quality determine cost; A real carat ruby, sapphire or emerald can be sold for $ 10 or $ 10,000 or more, depending on the quality of a particular gem. Authenticity does not mean that a gem is valuable. Only by taking the time to look at many gems, ask questions and make comparisons, you can develop and understand the differences that affect the rating of quality, beauty and value.
