Cameo Italiano "Victoria" 16x12mm Shell Portrait Cameo & Choice of Gem Ring

On the Mohs Scale, which measures the hardness of minerals, cubic zirconia is an 8.0 to 8.5. It is important to understand that hardness is not necessarily related to durability. Even though diamond is the hardest mineral (10.0 on the Mohs Scale), it can still be chipped or broken.

The only ways to tell the difference between cubic zirconia and diamond are by use of a thermal probe, by weighing the loose stone or by microscopic examination of surface features and inclusions. Cubic zirconia weighs approximately 65% more than diamond. Therefore, while a 6.25 mm round diamond weighs about 1.00 carat, the same size cubic zirconia weighs about 1.65 carats. If you know the weight of a cubic zirconia, you can figure out the diamond weight equivalent by multiplying the cubic zirconia weight by 0.6, or 60%.

Few natural diamonds on the market today are perfectly cut, and those that are cost much more than the usual diamond. Unleashing the fire, beauty and brilliance of a stone depends on its precise cut. Simulated diamonds are an excellent balance between quality, beauty and price.

Glossary

Brilliance: The white light leaving a jewel, traveling upward, which is visible to the eye. Brilliance is sometimes referred to as “sparkle.”

Dispersion: Flashes of rainbow colors. Also called “fire.”

Hardness: Resistance to scratching. The higher the number, the more resistant.

Luster: The shininess of a jewel.

Toughness: Resistance to breakage.

Turquoise:
One of the oldest known gems, turquoise has been prized for thousands of years. The Egyptians believed it had powerful mystical properties, and turquoise jewelry has been found interred with 7,500-year-old mummies. Ancient manuscripts from Persia, India, Afghanistan and Arabia say that the health of a person wearing turquoise could be assessed by variations in the color of the stone. Montezuma's treasure, now displayed in the British Museum, includes a carved serpent covered by a mosaic of turquoise.

Turquoise was especially revered by the Native American culture, an association that dates back to the Aztec empire more than 700 years ago. For the Aztecs, turquoise was reserved for the gods and mere mortals were forbidden to wear it. They believed it to be a gem of good fortune and a commodity more valuable than gold. Native Americans believed turquoise protected people from demons and they even placed turquoise in tombs to guard the dead. The stone's colors were thought to be symbolically blue for the heavens and green for the earth. Often warriors tied turquoise to their bows to ensure accurate shots.

Today, turquoise is still believed to provide protection and bring luck. It is said to also promote prosperity, love, healing, courage and friendship. The stone is thought to relax the mind and ease mental tension.

The gem's opaque turquoise color varies from shades of greenish blue to deep cobalt to sky blue. Some varieties display white or brown matrixes, which are streaks of the mother stone from which they came, while others have veins of black matrix running through them. Generally, the bluer the blue, the more highly valued the stone. A clear, even texture without mottling or veins is also preferred. The most rare and valuable color is an intense azure, but the most common is the mild to medium sky blue. Sometimes imitated by minerals such as chrysocolla, turquoise stones are often dyed or colored with coatings of various resins.

In the 13th century, turquoise was mistakenly believed to have come from the country of Turkey. Hence, its name came from the French word for Turkey, "Turquie". The stone was actually brought to Europe from Persia (now Iran), via Turkey. It is a mineral usually found in association with copper deposits and is sometimes mined as a by-product of copper mining.

Although turquoise is found in desert regions worldwide, especially in the southwestern United States, perhaps the finest and most valuable comes from the Sleeping Beauty mine in Globe, Arizona. It is named after the Sleeping Beauty Mountain which resembles a reclined woman in a slumbering state. Its turquoise is world renowned for its beauty that ranges from pure robin's egg blue to a darker royal blue.

While only ranking between 5.0 and 6.0 on the Mohs Scale of hardness, turquoise remains quite popular for jewelry. In Europe, turquoise rings are given as forget-me-not gifts, while in the United States, the stone is given as traditional 5th and 11th wedding anniversary gifts. It has even become a modern consideration for the December birthstone. When wearing turquoise over the years, the stone will absorb oil from a person's skin, causing a slight change to the color of turquoise.

Turquoise is commonly treated in various fashions to ensure its durability and visual appeal, especially when set in jewelry. If a stone has been treated, the type of process will be noted.

Turquoise is one of the oldest gemstones known in history going back 6,000 years BC and has been revered by almost every ancient culture. It is the alternate birthstone for December and has a Mohs rating of 5.0-6.0. Turquoise is a Hydrous Phosphate of Aluminum and Copper and may form as a chalky coating on rocks or finely disseminated crystals formed within small rock cavities. Rough such as this is not commercially viable, which has led to the development of reconstituted turquoise. Turquoise-bearing rock is pulverized and the turquoise is separated from the rock using a float process. The pulverized turquoise is then mixed with a colored resin, which is then injected into a mold to form a solid block. This is then cubed, preformed and fashioned into various shapes and sizes. It is an excellent method of using rough that would otherwise not be usable.