How GIA Grades Diamonds

Diamond Carat Weight Measurement
To determine carats, the diamond is weighed using an extremely accurate electronic micro-balance that captures the weight to the precise fifth decimal place (the nearest ten-thousandth of a carat). An optical measuring device is used to determine the diamond’s proportions, measurements, and facet angles. This data is uploaded into GIA’s computerized operations and information database management system.

Grading Diamond Color
Since light source and background can have a significant impact on a diamond’s appearance, color is graded in a standardized viewing environment against color masters. A minimum of two color graders enter their independent evaluations into the system and depending on the agreement of these grades, and the weight and quality of the diamond, it may be sent to additional graders who enter their own color opinions. The grade is not determined until there is sufficient consensus.

Diamond Clarity Grade
Diamond clarity is graded under standard viewing conditions with 10× magnification. The preliminary grader carefully examines the diamond in order to identify clarity/finish characteristics and evidence of any clarity treatments such as fracture filling or laser drilling.

A minimum of two graders assigns their impression of the diamond’s clarity, polish, and symmetry. Next they plot the clarity characteristics on the diagram most representative of the diamond’s shape and faceting style, selected from a database of hundreds of digitally stored diagrams. Also during this process the stone is screened to determine if it is synthetic.

Diamond Cut Grading
GIA provides a cut quality grade for standard round brilliant diamonds that fall into the D-to-Z color range. To develop their Cut Grading System, GIA performed extensive computer modeling of round brilliant diamonds over a 15 year period and conducted more than 70,000 observations on actual stones to validate the research. This system can now predict the cut grade for more than 38.5 million proportion sets.

GIA’s Diamond Cut Grading System assesses the diamond’s overall face-up appearance to predict the intensity levels of brightness, fire, and scintillation (the diamond’s sparkle and interplay with light). The result is a comprehensive Cut Grading System that accurately reflects all the critical cut factors of a round brilliant diamond.

Different Kinds of Pearls!!!

Multicolored Pearls

Peach Pearls

Black Pearls

White Pearls

Lavender Pearls

Pink Pearls

The Diamond Lattice

Molecules with all sp3-hybridized atoms can be visualized and drawn using a simple convention. The atom itself (and the bonds to it) are designated by one of two methods:

Draw three lines at 120 angles. One line will either point up or down.



If the vertical bond line goes up, add a fourth bond below the left-hand bond, displaced by 30. If the vertical bond line goes down, add the fourth bond above the right-hand bond, again displaced by 30.


The meaning implied by this convention is that the two bonds separated by 30 are going into and out from the plane of the paper, and the other two bonds are in the plane of the paper.


Note that these two are related by 180 rotation.

These two designators fit together in alternating positions to assemble any molecule you want. Extending it in all three directions makes the arrangement of atoms seen in the crystal lattice of diamond.



An important feature that helps you in the visualization is that, in this depiction, bonds that are parallel in the diagram are parallel in reality. To test this, make a model of a chair cyclohexane and compare to its diamond lattice representation:

Wedding & Engagement Rings : Diamond Engagement Ring Size

Gold is Gold

Gold is a soft, very dense metal which is highly valued for use in jewelry and coinage. Called a "noble metal", it does not react readily in ordinary chemical reactions, so it can be found in essentially pure form as gold nuggets. It is also used in dental work because it can be precisely shaped and does not react chemically in the mouth. Its high electrical conductivity makes it valuable for tiny electrical contacts, and its very high reflectivity has led to use in thin films as a reflector.

Gold is bright yellow by reflected light, but in thin films may be blue or green.

Gold is the most malleable and the most ductile of all metals. It can be hammered into sheets only 1/100,000 cm thick and drawn into wires 1/5000 cm in diameter.

Gold is often alloyed with copper, silver, palladium or other metals. The amount of gold in these alloys is described in carats. The carat value is the number of parts of gold in 24 parts of alloy, so that 24 carat gold is the pure metal. American coinage gold is 21.6 carat and British coinage is 22 carat.

White gold as used in jewelry is usually an alloy of gold and nickel.

Gold is found in the mineral nagyagite, a sulfide, along with lead, iron, antimony, and tellurium. Tellurium combines with gold to form krennerite, AuTe2.

How Pearls are Formed and Their Various Types?

There are essentially three types of pearls: natural, cultured and imitation. A natural pearl (often called an Oriental pearl) forms when an irritant, such as a piece of sand, works its way into a particular species of oyster, mussel, or clam. As a defense mechanism, the mollusk secretes a fluid to coat the irritant. Layer upon layer of this coating is deposited on the irritant until a lustrous pearl is formed.

A cultured pearl undergoes the same process. The only difference is that the irritant is a surgically implanted bead or piece of shell called Mother of Pearl. Often, these shells are ground oyster shells that are worth significant amounts of money in their own right as irritant-catalysts for quality pearls. The resulting core is, therefore, much larger than in a natural pearl. Yet, as long as there are enough layers of nacre (the secreted fluid covering the irritant) to result in a beautiful, gem-quality pearl, the size of the nucleus is of no consequence to beauty or durability.

Pearls can come from either salt or freshwater sources. Typically, saltwater pearls tend to be higher quality, although there are several types of freshwater pearls that are considered high in quality as well. Freshwater pearls tend to be very irregular in shape, with a puffed rice appearance the most prevalent. Nevertheless, it is each individual pearls merits that determines value more than the source of the pearl.

Regardless of the method used to acquire a pearl, the process usually takes several years. Mussels must reach a mature age, which can take up to 3 years, and then be implanted or naturally receive an irritant. Once the irritant is in place, it can take up to another 3 years for the pearl to reach its full size. Often, the irritant may be rejected, the pearl will be terrifically misshapen, or the oyster may simply die from disease or countless other complications. By the end of a 5 to 10 year cycle, only 50% of the oysters will have survived. And of the pearls produced, only approximately 5% are of substantial quality for top jewelry makers. From the outset, a pearl farmer can figure on spending over $100 for every oyster that is farmed, of which many will produce nothing or die.

Imitation pearls are a different story altogether. In most cases, a glass bead is dipped into a solution made from fish scales. This coating is thin and may eventually wear off. One can usually tell an imitation by biting on it. Fake pearls glide across your teeth, while the layers of nacre on real pearls feel gritty. The Island of Mallorca is known for its imitation pearl industry.

Where Pearls are Found?

Historically, the world's best pearls came from the Persian Gulf, especially around what is now Bahrain. The pearls of the Persian Gulf were natural created and collected by breath-hold divers. The secret to the special luster of Gulf pearls probably derived from the unique mixture of sweet and salt water around the island. Unfortunately, The natural pearl industry of the Persian Gulf ended abruptly in the early 1930's with the discovery of large deposits of oil. Those who once dove for pearls sought prosperity in the economic boom ushered in by the oil industry. The water pollution resulting from spilled oil and indiscriminate over-fishing of oysters essentially ruined the once pristine pearl producing waters of the Gulf. Today, pearl diving is practiced only as a hobby. Still, Bahrain remains one of the foremost trading centers for high quality pearls. In fact, cultured pearls are banned from the Bahrain pearl market, in an effort to preserve the location's heritage.

The largest stock of natural pearls probably resides in India. Ironically, much of India’s stock of natural pearls came originally from Bahrain. Unlike Bahrain, which has essentially lost its pearl resource, traditional pearl fishing is still practiced on a small scale in India.

The art of culturing pearls was invented in Japan in 1893 by a man named Kokichi Mikimoto. He discovered that by introducing a tiny bead of mother-of-pearl (the white substance on the inside of a mussel’s shell) into an oyster, that oyster would began to cover the irritant with nacre (the secreted substance that makes up a pearl). To this day, the Japanese are considered the foremost experts in seeding oysters and the Mikimoto family continues to be one of the largest pearl producing empires.



Interestingly, one of the first places to begin farming cultured pearls outside of Japan was near the Gulf of California in Mexico. Unfortunately, Mexican pearls disappeared from the international markets when overfishing of natural pearl oyster banks took its toll and the Mexican government had to impose a No- Fishing law in the late 1940's. Mexico is today attempting to return to the pearl market with cultured half-pearls (meaning they are only pearl slices or hemispheres, not round).

Pearls predominately come from Japan, Australia, Indonesia, Myanmar, China, India, Philippines, and Tahiti. Japan however, controls roughly 80% of the world pearl market, with Australia and China coming in second and third, respectively. The South Sea waters around Australia, Indonesia, and Myanmar are renowned for their large, white pearls, while Japan’s pearls are highly valued for their lustrous character. Freshwater pearls constitute the bulk of China’s pearl efforts. And as mentioned earlier, India is recognized as one of the last producers and handlers of naturally occurring pearls. Interestingly, although Australia’s pearls derive from the same sea as those from Indonesia and Myanmar, Australia consistently advertises their pearls as distinctly superior to other South Sea pearls, emphasizing the importance of the country of origin, not simply the body of water from which they came.