Read our comprehensive guide to buying gemstones here ( PDF file)
Color, Cut, Clarity and Weight all play key components in a gemstone purchase. We will cover these concepts and more in this article. When you buy a gem Most of the time color plays a big part in your purchase. Color is dependent on thechemical composition of the gem along with the cut,shape, the clarity and much more!
COLOR
Color is normally the first thing a buyer, You will look at, color alone does not make a gem desirable as you will learn, clarity, cut, and carat weight also come in to play. On-line a gem photo is all you will see, so a good description to accompany the photo is the best way to purchase your gem. First of all you need to understand colorrequires interaction of light, and the observer. Hue, tone and saturation all allow you to see the color you desire. Hue is the first basic impression of the basic color, Tone is the darkness of the color and Saturation is the color's strength or intensity. Color is important in any gem so as you order from your selected store on Gemrock your knowledge of gems will help you get the gem you want. Each gem has a unique Chemistry and structure that contribute to the gems unique body color. For example a ruby and sapphire are both varieties of the gem species corundum. The addition of a chromium 'ingredient' creates red hues we categorize as ruby. The presence of iron and titanium however generate blue hues of sapphire. Every gem we have grown to love has color variations due to chemical variations in each species or gem! Color Variation, Many customers expect to see a evenly spread colorthroughout the gem they buy, but many gems display more than one color and return light differently throughout their structure. All due to the chemical composition of the gem. Color zoning, There is areason for color zoning in gems. Mineral growth is never smooth. Growth conditions change for example a watermelon tourmaline may be pink on one end and green on the other, This is a desired color zone. Other gems may have color zoning that are not desired, some times a cutter can disguise that zone but that is not always possible. You may see a blue sapphire that is colorless on one end which can spoil the appearance of the gem. Take the type of gem you are buying into consideration when you see color zoning or a bi-color appearance. As stated color zoning may or may not add value to a gem.
COLORS look different in Different Lighting
Why do rubies look so rich in candlelight? Why does a woman's pale complexion glow like gold when she stands at an ocean pier at sundown? The answers all have to do with the way different light sources affect color. In general each gemstone looks different in specific light sources. Green, blue and violet gems look their est under the fluorescent lighting found in most offices. That's because fluorescent light typically gives off a lot of blue or green, this enhances these gem colors. Red, orange and yellow gems show their colors best in incandescent light, like candlelight, a regular lamp or the sun's rays at sunset. Incandescent light sources give off light waves mainly in red orange or yellow emphasizing these gem colors. If you remember that lighting affects the appearance of different colors this will help you when buying gems on-line, Also very important is each computer has different settings and may show a gem color somewhat different so please read descriptions or ask your seller about color. You may also need to realize that many cameras use UV Flash and other types of lighting that may cause color to vary a little from the actual gem. So I said, Questions are never unreasonable, A photo says a thousand words but a question can answer your concerns. Not every seller is able to spend the time and money on a Microscopic camera or other very expensive types of technology used by large companies. You will also want to consider 'FINE COLOR' The color in a gemstone color range considered by the trade to be most desirable. Your final choice should determine the color you choose. What industry selects is not always what you may select for your gem color. COLOR RANGE is the selection of color in which each gemstone occurs, color can play a big part on value of a gem, A rich 'AAA' color Tanzanite with a dark blue/violet color will be worth much more than a pale lilac colored Tanzanite gem in most cases. There are other things to take into consideration but color is one key component. Pleochroism is when a gem shows different body colors from a different direction, again we can use Tanzanite as a example, a top grade color Tanzanite may look violet / bluefrom one angle or purple from another. Tourmaline may look dark green at one end but appear much lighter green at another angle. Understanding gemstone colors can help you buy the perfect gem! The colors you will see in your gems are not only due to the chemical composition but cut, clarity and other factors will help you select the right gem.
Key terms:
- Play of color, the flashing rainbow colors seen in opal and some other gems.
- Aventurescene is the glittery effect caused by light reflecting from small flat inclusions within a gemstone
- Iridescence a rainbow effect created when light is broken up in to spectral hues by thing layers.
- Labradorescence is a broad flash of color in labradorite feldspar that disappears when the gem is moved.
- Aster-ism is the crossing of chatoyant bands, creating a star in the dome of the cabochon gem.
- Chatoyancy is the bands of light in certain gems caused by reflection of light from many parallel needle like inclusions or hollow tubes.
- Milk and honey is a two toned effect seen when chatoyant gem is positioned at right angles to a light source.
- Color change as seen in Alexandrite is very distinctive change in gem color under different types of light. This is very rare.
CLARITY
A major part of any transparent stone's value isit's clarity which is a freefrom blemishes and inclusion. A BLEMISH is a irregularity that 's confined to the surface of a polished gem. An INCLUSION on the other hand is enclosed within the gem or reaches the surface from the interiors. So it is important to know the difference. Many gems are graded on Inclusion inside the gem. The internal flaw. Colored stones have many kinds of blemishes and inclusions, with a variety of effects on a gem's appearance and durability.
Blemishes are surface irregularities such as scratches or nicks. They have little or no effect on the gemstones appearance and buyers need to understand once again a seller may not grade a gem on this basis but on Inclusion alone unless they are very large or numerous.
Inclusion on the other hand can affect a gem in many ways. The internal characteristics include breaks, pockets of fluid,foreign mineral crystals. Together Blemishes and Inclusion are called CLARITY CHARACTERISTICS.
Because of the way gems formatrulyinclusion freeor blemish free form is extremely remote. The fewer inclusions a gem has the rarer it is. And as you might guess the less inclusion seen the more valuable.
When buying a gem Inclusions should be considered by the following,
- Size: Large inclusions have more influence than the small inclusion.
- Number: In general termsthe more inclusion a stone has the lower the clarity. There are exceptions, a stone can have many minute inclusions and still be high on the clarity scale for that species.
- Position: Inclusions in the center of the table are usually more visible than those under the bezel or near the girdle.
- Color and relief: Inclusions that are close in color to the gem's body color do not stand out. but an inclusion that contrast with the gems body color like a red inclusion in a lighter colored stone will have a greater effect.
Beyond appearance a inclusion can affect the gems durability. In many cases inclusions that affect durability have a major influence on value. Breaks fall in to this category.
Typically only a few colored gems are usually inclusion free, those gems are aquamarine, Citrine, Kunzite, Tanzanite, and topaz, In contrast red tourmaline and emeralds always have some amount of inclusion.
Helpful inclusion, remember some inclusion can be helpful, needle like inclusion such as seen in cat's eye gems or the horsetail inclusion seen in a demantoid garnet will create such value the inclusion is the center point of the gem!!
Inclusion is helpful since they help us separate natural gems from synthetic! A finger print of a sort, each gem has its own characteristics and inclusion is one way we can identify most gems.
What you must ask yourself is does the gem have inclusion or breakage that will affect the durability of your gem? Will the inclusion cause the value of your gem to be below average cost. Does the inclusion take beauty away from your gem? Consider all these things when looking at inclusion inside your gem.
CUT
When we talk about the cut of a polished stone we are referring to one of two combinations - its shape and style or its proportion and finish. After color, shape and style are usually the first thing we notice in a gem. Shape is the stones face up - outline. The round is the most familiar shape. All others are generally classified as fancy shapes. These include Emerald, Cushion, Oval, Pear, Marquise and Heart. Style is the way the cutter arranged the stones facets. Most gems are faceted in one of three styles. the brilliant cuts facet (top) radiate from the table or culet to the girdle. The step cut's facets (center) the arranged in concentric rows. the mixed cut (bottom) combined a brilliant - cut crown with a step base. Beside these basic styles cutters can create countless variations by adding, subtracting and rearranging facets! Some gem crystals develop typical shapes and sizes that lend themselves well to certain cuts. For instance the rough of Emeralds lend themselves to rectangle cutting styles like the emerald cut. Rubies and Sapphires over a carat rough are typically cut in a oval or cushion cut. A quality cut helps a gem reach its highest potential for attractiveness. A cutters goal is to retain weight from rough while fashioning the most attractive gem. Not all gems can be cut in a traditional way when a cutter wants to retain weight. If a special settings is to be made for the gem you will have a piece of art. Calibrated cuts are gems that will meet standard sized mountings, if a gem size is not even close to the standard size you will need to have your jeweler adjust your mounting. Many higher quality gems like a ruby are usually not cut to standard industry dimensions because to much weight is lost in cutting. Designer cuts and Fancy cuts are artistic gem cuts that normally don't fit standard size mounts but still easily set in a mounting by a skilled Jeweler. For the most part smaller stones are normally cut into standard sizes and larger gems are cut symmetrically if possible to highlight important value factors. Don't forget a standard mounting can usually be adapted to hold the gem of your dreams, Irregular size gems at the very top end of the quality and value scale often require and get Custom settings!
CARAT WEIGHT
Worldwide Jewelry industry uses the Metric Carat (abbreviated ct.) A point is equal to 0.01 of a carat So your gem may way 7.96 ct. It is important to remember that although carat weight is a value factor, it isn't the deciding factor in either quality or beauty. A 1.00 ct. gem can be as fine as a beautiful 10.00 ct. stone if not perhaps as spectacular. It all depends on the individual stone and the customers preference. Quoting weights - Sellers often discuss carat weight in ranges, using fractions such as one quarter carat or one half carat as general references. But a wholesaler offering a .27 ct. gem may offer the gem as a quarter carat gemstone. In casual conversations between sellers a quarter carat stone can weigh between .23 - .29 ct. but in sales presentations your seller needs to be very careful using fractions like one quarter or one half, You really need to know the exact weight or within 0.01 - 0.02 ct weight, many scales will differ by that amount, if you seller uses a good scale you will normally be within 0.01 or exact weight. Accuracy is also crucial when describing total gem weight in a gem. This is to avoid any type of confusion on the customers part so if you do not understand the weight Ask! Typically you will find several gemstone sellers you like and trust to buy gems from, You should be able to trust a quoted weight. A wholesale seller may quote prices in two ways per stone or per carat price. The stone price is the total price per stone.The carat price will be per carat, if the gem is selling at 50.00 a carat and you buy a 3 ct. gem you will pay $150.00. Weight and value - Some gems normally occur in smaller sizes. Gem quality rough rubies, Alexandrite are good examples of a gem that are typically smaller than a 4 ct. size. other gems like Aquamarine and Citrine or amethyst and topaz occur in very large crystal up to 100 ct. With such gems there's usually little or no increase in per carat price with size. A 4 ct. amethyst typically cost twice as much as a 2 ct. amethyst. The price of a 1 ct. ruby and a 3 carat ruby can be very different due to the value of the gem. WEIGHT VS. SIZE - You may have two gems similar in size, for instance a aquamarine and a blue topaz of the same size will offer a topaz with greater weight than aquamarine's weight. In the same scenario a 1 ct. Sapphire and a 1 ct.Iolite that weight the same will have different dimensions.. so do be careful when changing stones out of mountings, They weight and dimension are different between stones. So now you realize you need to consider a range of COLOR when you pick a gemstone, You will need to look at the clarity of the gem, the cut and weight. In the end the choice is up to you, Choice of color is a personal decision. but the clarity of your gem does matter. The cut will also matter, the gem you select should have a nice proportion and design. A poor cut is easily seen through the window or dark spots of a gem. A beautiful gem with a nice sparkle will catch the eye of any gem lover. Lastly a seller you trust and have worked with before is best, On gemrock the sellers are to comply with site regulations, If you have questions of your seller ask,they should be able to answer almost any question you have about the gem listed. If you do not feel enough information is given I am sure your seller will be happy to provide you with the help you need. Most are willing to help withmountings if requested or special order gems. A trusted verified seller is a great prize!
Karen Del Gaudio
Last Update: 3 Aug