Color: Color is a measure of the diamonds transparency. As a rule, the more colorless the better. Again there are two systems of measurement. The American Gem Society uses a numbering system of zero to 10, zero being completely colorless. The Gemological Institute of America uses a letter system of D through M, D being completely clear.
D: Absolutely colorless. The highest color grade, which is extremely rare.
E: Colorless. Only minute traces of color can be detected by an expert gemologist. A rare diamond.
F: Colorless. Slight color detected by an expert gemologist, but still considered a "colorless" grade. A high-quality diamond.
G-H: Near-colorless. Color noticeable when compared to diamonds of better grades, but these grades offer excellent value.
I-J: Near-colorless. Color slightly detectable. An excellent value.
K-M: Not carried.
N-Z: Not carried.

A good cut gives a diamond its brilliance, which is that brightness that seems to come from the very heart of a diamond. The angles and finish of any diamond are what determine its ability to handle light, which leads to brilliance.

As you can see in the image below, when a diamond is well-cut, light enters through the table and travels to the pavilion where it reflects from one side to the other before reflecting back out of the diamond through the table and to the observer's eye. This light is the brilliance we mentioned, and it's this flashing, fiery effect that makes diamonds so mesmerizing.

Clarity: Clarity grades the formation and condition of the diamond, both internal and external. Tiny voids and cracks, misaligned crystals, and common nicks and scratches all lessen the value of the stone. There are two systems used in grading the diamond. The American Gem Society use a numbering system from zero to ten, zero being perfect. The Gemological Institute of America uses the following system:

Color: When purchasing pearls, the first decision is what color to choose. Freshwater and Akoya pearls are white rosé, while South Seas pearls are silver-white, and Tahitian pearls are silvery-black. When buying jewelry with more than one pearl, be sure the pearls match in color.

Luster: Pearls produce an intense, deep shine called luster.
The intensity of a pearl's luster is determined by the
thickness of a pearl's nacre (pronounced NAY-ker) —
the semi-opaque layers of calcium carbonate that make
up the pearl. Luster is the result of light reflected off of a
pearl's nacre. High luster makes a pearl appear to glow.

Luster is rated from very high to very low. Pearls with high
luster return sharp, almost mirror-like reflections, and
present high contrast between the reflections of light and dark.

Shape: The most desired pearl is round in shape. The closer a pearl comes to being perfectly round, the greater its value. Acceptable ranges for round pearls are "all round" to "slightly off round."

Sizes: Pearls come in a range of sizes. They are classified by the measurement of their diameter in millimeters. While a particular size may be considered large in one type of pearl, that size may be smaller than average in another type of pearl.

Surface: Like diamonds, pearls are rarely flawless. Each pearl is unique and usually has small surface imperfections on its "skin" that are commonly described as blisters, spots, or indentations.

For pearls with very few surface markings, look for pearls with surface markings listed as "Flawless," but for a better value, look for pearls with surface markings listed as "Slightly Spotted."

Shapes & Cutting Styles: When gemologists speak of a gem's shape, they usually mean its face-up outline. The most common gemstones shapes include the round, oval, square, triangle, pear, marquise, heart ans cushion. Cutting style refers to the way in which stone is cut or faceted. Emerald Cut shape is rectangular with clipped-off corners and that the faceting style is a step cut, which has parallel rows of long, four sided facets.


Carat Weight: The weight of small stones is frequently expressed in points, with one point equalling 0.01 carats. There are 100 points in one carat and one carat carat equalling 1/5 of a gram. For example, five points is the same as five-hundredths of a carat. Contrary to the popular belief, jewelers do not use point to refer to the number of facets of a stone. Note that point when used in expressing weights over one carat refers to the decimal point, not a unit of measure.


Size: Sometimes in the jewelry trade, the term "size" is used as a synonym for "carat weight." This is because size and weight are directly related. However, as gems increase in weight, their size becomes less predictable. Therefore, you need to consider stones measurements as well as carat weight when buying colored stones. For gemstone approximate carat weights click here.


Judging Color: Depending on whom you talk to, sherry-colored topaz is either yellow, orange, yellowish brown or reddish. That's because people have different opinions as to what is the color of sherry. For a more precise and accurate description of gems, it's helpful to divide color into the three components as used by Gemological Institute of America (GIA) and the American Gemological Laboratories (AGL). The three components of color are: hue, tone, and color purity.


Hue Tone Saturation: Hue refers to the basic colors of blue, gren, yellow, orange, red, purple and violet. Tone refers to the depth of color (light or dark). The lighest possible tone is colorless. The darkest is black. Saturation (color purity) is the brightness or vividness (dullness or drabness) of the color. It refers to the degree to which the hue is hidden by brown or gray.


Clarity & Transparency: Clarity and transparency are very important value factors for gemstones, sometimes even more important than color. Consider, for example, emeralds or sapphires. No matter how grayish, brownish, and/or light-colored they are, they're still gems if they are transparent and eye clean. The term clean by itself mean that a stone is of high clarity. However, if they are opaque and filled with deep cracks and eye-visible flaws they're industrial grade stones, even if they have desirable color.


Judging Cut: Cut plays a major role in determining the value of colored gems because its affects their color and clarity as well as well as brialliance. For example, a stone that is cut too shallow can look pale and lifeless, and it can display flaws that would normallyt not be visible to the naked eye. The term cut is sometimes confusing because it has a variety of meanings.


Treatments: A treatment is any process such as heating, oiling, irradiation, waxing, dying or bleaching which alters the color or clarity of a gem. Enhancement is often used as another word for treatment. Enhancement also refers to the faceting and polishing of a gem. If stones are improperly heated, for example, they may become brittle, causing them to abrade more easily. Some treatments are not stable. For centuries, gems have been in heat treated to improve their color. Heat treating is widely accepted because it's a continuation of a natural process and it causes a permanent improvement of the entire stone. However, a premium may be charged for high-quality untreated stones that comes with a lab report stating that there is no evidence of heat treatment.


Snythetic Stones: It describes a gemstone made in a lab which has the same basic chemical composition and similar chemical, optical and physical properties to its natural counterpart. A natural gemstone comes from the ground and is a product of nature, not of man. Immitations, on the other hand, do not have the same chemical composition as the stones they resemble, and they mkay be made by nature or by man. Cultured is sometimes used as a synonym for "lab grown." The two terms, however, are not equivalent. Cultured pearls are not synthetic. Created gems are grown in a lab, not in a natural environment such as a ground.


Deceptive Practices: Foil Backing; and Assembled Stones are all deceptive practices. Fraud occurs when a customer is not told that his stone is synthetic or treated.

Rope Chain: It's sturdy especially compared to hollow rope chain and flat chains like the herringbone. The thicker the chain, the stronger it is. It's ideal for suspending pendants and charms. However, heavier the pendant, the thicker the chain should be. Eventhough it can be repaired to look like new, it's not easy to repair as a solid link chain. Hand-made rope however is easier to repair than the machine-made type.

Diamond Cut Rope: The tiny flat surfaces on the chain reflect light like the facets of a gemstone and give the chain a brighter look. The process of cutting these surfaces is called diamond cutting. Since diamond-cut rope sparkles more than the standard rope, it tends to sell better. Some jewelers have had customers complain that diamond-cut rope snags their clothes. Other jewelers say their customers are pleased with it. The cause of this discrepency is probably that the chains are made by different companies. Part of the problem may be the use of old instead of new diamonds to cut their facets. When buying diamond-cut rope, brush it with your clothing and run lightly through your fingers to see if it snags or scratches.

Handmade Rope: Considering its complexity, handmade rope is relatively inexpensive. There are various qualities of handmade rope. A high quality 14k rope will have:

.a flexible, tight weave, giving its strength.

.a smooth, well finished surface.

.links of 14k plumb gold.

.14k solder instead of low-karat solder.

A good way to compare the weave is to twist rope slightly. A loosely assembled rope will untwist to a larger length than one which is tighter.

Advantages:

It' strong and a good chain for pendants. I's easy to repair and it's flexible and hangs nicely.

Disadvantages:

It generally costs more than herringbone chain of the same width because it weighs more. It's usually not as flashy as a herringbone chain.

Flat Chain: The most popular flat chain on the market is the herringbone. Some jewelers won't stock it as it kinks so easily.

Advantages:

It offers a big look at low price. The flatness of the chain makes it wider than other types of chain of the same weight and price.

It often looks shiner than rope and link chain. This is due to light reflecting off a broader surface area.

It's available in a wide variety of styles and finishes.

Disadvantages:

It's not durable.

It's not a good chain for pendant.

It is hard to repair it properly.

Link Chain: Solid-link chains get the highest rating from jewelers and chain dealers alike. Link chain comes in wide variety of styles. One that is particularly popular in anchor chain. Virtually, it is often refered to the Gucci chain. Another popular link chain is the figaro. It usually has an alternating pattern of one large and three small lnks. Linl chain s also comes in wide variety of sizes- from the small, basic chain termed cable to striking jumbo necklaces and bracelets. Normally the thicker the link the stronger itis, provided it is solid and well soldered. A link chain that has been twisted about 85 degrees and then flattened is often called a curb link.

Box Chain: Most of the box chains in the market are small and lightweight. As its name indicates, this chain looks like a line of little boxes linked together. It's most frequently used to hang pendants and charms. Naturally, the thicker the box link will be, the stronger the chain will be.

Due to its flat surfaces which reflect light, box chain may look brighter than some other small chains. Box chain might break if it is very thin, and some of it does not allow pendants to roll as easily as a rope or cable chain.