About Gemstones

Diamonds

The Four C's

The four most important factors used to measure diamond quality are Carat, Color, Clarity and Cut. The combination of these factors are used to determine the value of the stone.

Carat: Carats are sometimes confused with the term "size", but is more accurately described as "weight". A full carat is equal to 200 milligrams, or 1/5 of a gram. A carat is also divided into 100 parts, so the term .75 carats is the same as saying 75/100 of a carat, or 3/4 carats. The rarity of diamonds goes up exponentially to the size, along with the value. A high quality 5 carat diamond is much more valuable than 5 individual diamonds that are 1 carat each.

Color: Diamond color is all about what you can’t see. Diamonds are valued by how closely they approach colorlessness – the less color, the higher their value. (The exception to this is fancy-color diamonds, such as pinks and blues, which lie outside this color range.)

Most diamonds found in jewelry stores run from colorless to near-colorless, with slight hints of yellow or brown.

The Gemological Institute of America's color-grading scale for diamonds is the industry standard. The scale begins with the letter D, representing colorless, and continues with increasing presence of color to the letter Z, or near-colorless. Each letter grade has a clearly defined range of color appearance. They do not use the letters A, B, or C to avoid conflict with previous grading systems that were in use throughout the world.

Clarity: Because diamonds formed deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes).

Diamond clarity refers to the absence of these inclusions and blemishes. Diamonds without these birthmarks are rare, and rarity affects a diamond’s value. Using the Gemological Institute of America's International Diamond Grading System, diamonds are assigned a clarity grade that ranges from flawless (FL) to diamonds with obvious inclusions (I3).

Every diamond is unique. None is absolutely perfect under 10× magnification, though some come close. Known as Flawless diamonds, these are exceptionally rare. Most jewelers have never even seen one.

The GIA Clarity Scale contains 11 grades, with most diamonds falling into the VS (very slightly included) or SI (slightly included) categories. In determining a clarity grade, the GIA system considers the size, nature, position, color or relief, and quantity of clarity characteristics visible under 10× magnification.

Flawless (FL) No inclusions or blemishes are visible to a skilled grader using 10× magnification.

Internally Flawless (IF) No inclusions and only blemishes are visible to a skilled grader using 10× magnification.

Very, Very Slightly Included (VVS1 and VVS2) Inclusions are difficult for a skilled grader to see under 10× magnification.

Very Slightly Included (VS1 and VS2) Inclusions are clearly visible under 10× magnification but can be characterized as minor.

Slightly Included (SI1 and SI2) Inclusions are noticeable to a skilled grader using 10× magnification.

Included (I1, I2, and I3) Inclusions are obvious under 10× magnification and may affect transparency and brilliance.

Cut: Cut is the factor that fuels a diamond’s fire, sparkle and brilliance. The traditional 58 facets in a round brilliant diamond, each precisely cut and defined, are as small as two millimeters in diameter. But without this precision, a diamond wouldn’t be nearly as beautiful. The allure of a particular diamond depends more on cut than anything else.

Though extremely difficult to analyze or quantify, the cut of any diamond has three attributes: brilliance (the total light reflected from a diamond), fire (the dispersion of light into the colors of the spectrum), and scintillation (the flashes of light, or sparkle, when a diamond is moved).

An understanding of diamond cut begins with the shape of a diamond. The standard round brilliant is the shape used in most diamond jewelry. All others are known as fancy shapes. Traditional fancy shapes include the marquise, pear, oval and emerald cuts. Hearts, cushions, triangles and a variety of others are also gaining popularity in diamond jewelry.

As a value factor, though, cut refers to a diamond’s proportions, symmetry and polish. For example, look at a side view of the standard round brilliant. The major components, from top to bottom, are the crown, girdle and pavilion. A round brilliant cut diamond has 57 or 58 facets, the 58th being a tiny flat facet at the bottom of the pavilion that’s known as the culet. The large, flat facet on the top is the table. The proportions of a diamond refer to the relationships between table size, crown angle and pavilion depth. A wide range of proportion combinations are possible, and these ultimately affect the stone’s interaction with light.

Birthstones

Metals

Gold is a primary element, which means that it is a not a mixture of various atoms, but is made up of atoms that are all alike. Pure 100% gold is very soft, and is not suitable for jewelry because it would be easily damaged. Therefore, to make gold jewelry, we must mix it with other materials to harden it. As we increase the mixture of these other materials, we lessen the purity of the gold, so we need a measure to specify how much gold there is compared to the other hardening materials.

The measurement for gold purity is called "karat", not to be confused with diamonds weight measurement, "carat". When the term karat is used with gold, 24 karats are deemed 100% pure gold. Usually, gold is mixed with a metal like copper or silver when making jewelry. This is called an alloy, or the combination of different metals. Each karat indicates 1/24th of the whole. So if a piece of jewelry is made of metal that is 18 parts gold and 6 parts copper, that is 18-karat gold, or 3/4 gold and 1/4 copper. You may see gold as 14 karat, or even as low as 10 karat.

Yellow gold is generally a mixture of gold and copper. White gold is generally a mixture of gold and nickel, although palladium can be used as a more expensive additive for people whose skin is sensitive to nickel. Mixing the gold with silver produces a white gold with a slight green tinge to it. Pink and rose tones can be created by adding a higher concentration of copper to the alloy.

Platinum is a rare precious metal that's used to create fine jewelry. Its heavy weight and durability make platinum a metal that will not wear away with constant use. Platinum holds fine gemstones firmly in place for the life of the jewelry when used as prongs and other setting components. Platinum's natural white luster provides a rich backdrop for diamonds, but it's a metal that's just as elegant when used all by itself to create a piece of jewelry, either a simple polished item or a design with engraved motifs. Platinum looks stunning when combined with contrasting touches of 18K yellow gold.

The Platinum Group of Metals
Six related metals belong to the Platinum Group of Metals, or PGM:

Platinum
Iridium
Palladium
Ruthenium
Rhodium
Osmium

Platinum Marks
Jewelry can contain different percentages of pure platinum. The US Federal Trade Commission, FTC, publishes guidelines for acceptable marking standards for platinum jewelry sold in the US. Platinum content is usually expressed as the amount of pure platinum the jewelry contains in parts per thousand. Think about it like this... you mix up a huge bucket of fruit tea that contains 1,000 ounces--900 hundred of the ounces are plain tea and 100 are fruit juice. That makes the tea 900 parts per thousand of your mix. Another way to express that is to say that tea makes up ninety percent of the mix--900 divided by 1000.

Jewelry that contains at least 950 parts per thousand of pure platinum may be marked or described as "Platinum"

Jewelry that contains 850, 900 or 950 parts per thousand of pure platinum may be marked "Plat" or "Pt" if a number is used in front of the term to disclose the amount of pure platinum in the mix, such as "850 Plat" or "850 Pt", or "950 Plat" or "950 Pt".

Jewelry that contains at least 950 parts per thousand of platinum group metals, with at least 500 parts per thousand of the total pure platinum, may be marked as platinum as long as the numbers of each metal are disclosed. For instance, "600 Pt. 350 Ir." or 600 Plat. 350 Irid." for 600 parts pure platinum and 350 parts iridium "550Pt. 350Pd. 50Ir." or "550Plat. 350Pall. 50Irid." for 550 parts pure platinum, 350 parts palladium and 50 parts iridum.

Silver by itself is too soft to create durable jewelry, so it's mixed with other metals to enhance performance. One popular silver mixture, an alloy, is known as sterling silver.

The US Federal Trade Commission (FTC) stipulates that jewelry sold in the United States cannot bear silver markings or be described as silver, solid silver, sterling silver, sterling, or with the abbreviation Ster. unless it contains at least 92.5 percent pure silver. The minimum silver content can also be stated as 925 parts per thousand of pure silver, so you might see the figures 925 or 92.5 used to designate silver content.

Copper is the metal most commonly used to make up the remaining 7.5 percent content of a sterling silver mix. Copper makes the silver harder, but gives it a tendency to tarnish, a darkening that occurs when sterling silver reacts with gases in the air or with other substances that it comes in contact with.

Caring for Sterling Silver Jewelry
Store your sterling silver jewelry in tarnish prevention cloths or bags. The treated cloth slows down the tarnishing process and keeps the jewelry from rubbing against harder jewelry that might scratch it. Try to to keep your sterling silver jewelry in a cool, dry place.

Cleaning Your Sterling Silver Jewelry Polishing cloths are an excellent choice for cleaning your sterling silver jewelry. You might read recommendations to use toothpaste to clean sterling silver, but avoid doing that -- toothpaste is abrasive and can leave scratches.

Sterling silver jewelry that is worn continually often develops a lovely patina, a kind of glow combined with darkened areas. If you like the look, leave it alone. If you prefer a bright and shiny look for your sterling silver, use a polish cloth to restore the jewelry to its original appearance.