Understanding Diamond "4 C's"
Carat Weight
Clarity
Color
Cut
The "4 C's" really are important.
Carat
Diamond Carat Weight
Diamonds are sold by the carat. One carat = 0.20 grams, or 1/5 th of a gram. Wholesale prices are normally quoted per carat, not by the gem. It is a quick easy reference for comparison.
Certain diamond sizes usually command higher prices per carat ... break points, so to speak. A diamond of .5 or .51 carats will be worth more per carat than an equal quality stone of .49 carats. Other break points are 1 carat, 2 carats, etc ... and prices increase exponentially.
Clarity
Diamond Clarity
Clarity describes the absence or presence of included crystals, voids, cracks, fissures, etc. which might be present in a diamond; observable by a trained individual with normal eyesight while using a 10X loupe. The size, location, distraction and number of the characteristics are compared to a set of established industry standards.
Color
Color, for non-fancy diamonds; white, or colorless is considered ideal. Color is determined using a master set of stones with color grades established by a standards lab. Diamonds are color-graded pavilion up ... upside down, so to speak.
Grading starts with D being considered colorless. The variations between D and E are so minor that only an expert with good color balanced eyesight and with proper lighting in a correct environment can see the gradation.
Diamond color grades tend to be stated in sets of 3. D-E-F is the whitest grade.
Yellow and brown are considered least desirable, with gray next and blue better.
Color grading should never be attempted on a diamond in a mounting since metal colors; or any hidden color-aids cannot be eliminated.
Example: the slightest mark on the girdle of a diamond with a blue felt tip pen can mask yellow and improve the apparent color grade of the diamond significantly.
Diamond Cut
Cut may be the most important of the C factors. A well fashioned diamond should be symmetrical, proportioned to take advantage of the optical properties of diamond, and polished to a high quality standard.
Symmetry, either 2 way symmetry (heart, pear); or 4 way symmetry (round, oval, emerald, marquise, cushion, radiant) is a crucial factor in displaying the beauty of a diamond.
Diamond Proportion
Proportion, the rewsult of good cutting, makes a diamond do what it is supposed to do; direct the maximum amount of light entering the gem to the eye of the observer.
Diamond characteristics are determined by nature and physics. Significant deviation from certain angular proportions will result in a less appealing gem.
Spread = dead. Light will leak out the pavilion and dull the gem's appearance.
Facet junctions should be crisp, not "rolled".
Facet corners should meet perfectly.
Girdle should be straight rather than wavy
Girdle should not be overly thin or could reduce the diamond's durability.
Overly Thick girdles will result in smaller appearing diamond for the same carat weight
A large culet may be a way of reducing color.
Monday, June 21, 2010
How are Gemstones Formed?
How are Gemstones Formed?
Gemstones are formed in several specific and different ways. Their colors are almost always a result of their chemical composition while they form.
Turquoise
Turquoise forms when water moves through a rock containing copper, aluminum, and phosphorus. Turquoise often occurs in arid or desert environments, such as the Southwestern part of the United States. You may be familiar with beautiful Native American jewelry from the Southwest, which is often made with turquoise.
Garnet
People commonly think of garnets as being red, but they are found in many colors ranging from yellow to black. Color-changing garnets look different when viewed in daylight and incandescent light.
Garnets often form in hot metamorphic rocks under great pressure. Garnets occur in every color. Their color is determined by the chemical composition of the melted mineral mix as it solidifies. Red garnets, or pyrope, get their color from magnesium silicate, the melted chemical mixture in which they form.
Jade
Jade was a highly-valued material used in burial ceremonies, royal crowns, jewelry and for the hieroglyphics of many cultures such as the Olmecs of Mesoamerica and Chinese.
Jade is a gem that can be cut and polished from two minerals: jadeite and nephrite. Both minerals form in metamorphic rocks at high temperature and under high pressure deep within the earth.
Gemstones are formed in several specific and different ways. Their colors are almost always a result of their chemical composition while they form.
Turquoise forms when water moves through a rock containing copper, aluminum, and phosphorus. Turquoise often occurs in arid or desert environments, such as the Southwestern part of the United States. You may be familiar with beautiful Native American jewelry from the Southwest, which is often made with turquoise.
Garnet
People commonly think of garnets as being red, but they are found in many colors ranging from yellow to black. Color-changing garnets look different when viewed in daylight and incandescent light.
Garnets often form in hot metamorphic rocks under great pressure. Garnets occur in every color. Their color is determined by the chemical composition of the melted mineral mix as it solidifies. Red garnets, or pyrope, get their color from magnesium silicate, the melted chemical mixture in which they form.
Jade
Jade was a highly-valued material used in burial ceremonies, royal crowns, jewelry and for the hieroglyphics of many cultures such as the Olmecs of Mesoamerica and Chinese.Jade is a gem that can be cut and polished from two minerals: jadeite and nephrite. Both minerals form in metamorphic rocks at high temperature and under high pressure deep within the earth.
How to describe the Gems ?
How Can You Describe a Gemstone?
Gemstones are described by specific gravity, hardness, and color. These are all features of minerals.
Specific Gravity
Specific gravity is a measure of how much heavier a mineral is than an equal amount of water. Tourmaline has a specific gravity of 3.03 to 3.25. This means that it is a bit more than three times as heavy as water.
Hardness
You can see that topaz has a hardness of 8 on the scale. This means that a topaz is harder than anything except a sapphire or a diamond
Color
How would you describe turquoise? You’d probably say it’s blue-green. Gemstones are described according to their color because it’s a useful characteristic. Diamonds are clear, but can be tinted yellow, pink, or even black from the presence of other minerals.
Rare and highly valuable diamonds in colors of blue, yellow, red and pink occur only in one in every 100,000 diamonds
Gemstones are described by specific gravity, hardness, and color. These are all features of minerals.
Specific Gravity
Specific gravity is a measure of how much heavier a mineral is than an equal amount of water. Tourmaline has a specific gravity of 3.03 to 3.25. This means that it is a bit more than three times as heavy as water.
Hardness
Hardness is the resistance of a mineral to scratching. Geologists use a measurement called Mohs’ scale to describe the hardness of a mineral.
You can see that topaz has a hardness of 8 on the scale. This means that a topaz is harder than anything except a sapphire or a diamond
Color
How would you describe turquoise? You’d probably say it’s blue-green. Gemstones are described according to their color because it’s a useful characteristic. Diamonds are clear, but can be tinted yellow, pink, or even black from the presence of other minerals.
Rare and highly valuable diamonds in colors of blue, yellow, red and pink occur only in one in every 100,000 diamonds
Where are Gemstones Found?
Gemstones occur in locations all over the world.
Diamonds are found deep within the earth in a rock called kimberlite.
Tourmaline and beryl are found in stream beds after they erode from surrounding rocks.
And garnet is often found in a rock called gneiss, which has been heated to high temperatures.
Diamonds are found deep within the earth in a rock called kimberlite.
Tourmaline and beryl are found in stream beds after they erode from surrounding rocks.
And garnet is often found in a rock called gneiss, which has been heated to high temperatures.
What is Gemstone?, What is a Gem
What Is a Gemstone? What Is a Gem?
Have you ever seen a diamond in a ring?
Gemstone
Have you ever seen a diamond in a ring?
An opal in a necklace? A pearl earring? Diamonds, opals, and pearls are types of gemstones.
A gemstone is a mineral, rock, or organic material that is used for jewelry, ornamentation, or art. A gem, such as a diamond, is a type of gemstone that must be cut and polished for its beauty to be visible. Opals and pearls may be styled into jewelry or art without any cuts or polishing. They are gemstones,
but not gems.
Gemstone Gems
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