In order to determine the karat weight of a specific item, simply look for the quality mark. Jewelry items will bear the stamp of their karatage based upon the United States or European system of marking. The United States system designates pieces by their karats—24K, 18K, 14K, 10K, etc. The European system designates pieces by their percentage of gold content. For instance, 10K gold is marked “417,” denoting 41.7% gold; 14K is marked “585,” denoting 58.5% gold; and 18K is marked “750,” denoting 75% gold; etc.
Jade:

Jade reigns as the universal symbol for good luck and has been treasured in China as the royal gemstone for 5,000 years. The Chinese character for jade resembles a capital “I” with a line across the middle. The top of the character represents the heavens, the bottom the Earth and the center section humankind. It has been considered a symbol of love, virtue and status for thousands of years and remains popular today. Jade is traditionally given as a 12th anniversary gift and is believed to strengthen the body and bring longevity to life.

Jade is the term applied to forms of both jadeite and nephrite. The ancient jade carved in China was what we today call nephrite. In the nineteenth century, it was discovered that the material from the new world was not the same mineral as the jade from China. This new and different jade from Central America was called jadeite to distinguish it from the original nephrite. Both are similar in appearance, yet jadeite is considered the true jade and commands higher prices. Though both are quite durable and tough, ranking 6.5-7.0 on Mohs Scale, jadeite is slightly harder than nephrite due to its microcrystalline structure.

Jadeite has a much more vivid green color with finer translucency than nephrite. It is most treasured for its vivid greens, but it also comes in lavender, pink, yellow and white. Nephrite, however, is found in less intense spinach green, white, brown and black colors. While overall color is the most important factor in considering the value of jade, other important criteria are translucency, texture and pattern. Jade is most often sold by the piece rather than per carat. Because of its smooth and even texture, it has long been a preferred material for carving. When placed in jewelry, it is usually cut into smooth dome shapes called cabochons.

Jadeite is primarily mined in Myanmar. Each year, the state-owned Myanmar Gems Enterprise holds the Myanmar Gems, Jade and Pearl Emporium where boulders are sold to top jade dealers from around the world. The dealers take some high-risk gambles with the jade boulders they purchase. Boulders are sold intact, with only a tiny window cut in the side to expose a small section of the interior. The buyer has no idea what lies inside, whether there is valuable green jadeite or only white or brown-stained inexpensive material. Relying on instinct, buyers pay hundreds of thousands of dollars for what may turn out to be exquisite gemstones or huge losses.

The most valuable form of jadeite is known as imperial jade. It is a vivid emerald green color and comes from Myanmar. The Emerald Buddha, a sacred image that is enshrined at Wat Phra Kaeo in Bangkok, Thailand, is actually beautiful green jadeite. A leek green variety called "Russian Jade" is found near Lake Baikal in Russia. In addition to Myanmar, small quantities of jadeite can be found in Mexico and Central and South America, while nephrite is mined in Australia, Canada, Taiwan and the United States.

In ancient China, Jade was thought to preserve the body after death and was placed in emperors' tombs. One tomb contained an entire suit made of jade, thought to assure the physical immortality of its owner. In Central America, the Olmecs, Mayans and Toltecs also treasured jade and used it for carvings and masks. In Europe, although prehistoric axes and blades carved from jade have been found by archeologists, the gemstone was not popular for jewelry use until the sixteenth century when jade objects were imported from China and, later, Central America. The Portuguese brought home jade pieces from their settlement in China and called jade “piedre de ilharga,” which meant “stone of the loins” because they believed it to be strong medicine for kidney ailments. Jade objects brought to Spain were called by the Spanish version of this phrase, “piedra de hijada.” This became the French word “ejade,” which led to the English word jade.

Tiger Eye:

Tiger eye, also called tiger’s eye, received its name because it has rich yellow and golden brown bands resembling an eye of a tiger. The stone is a common form of brown quartz that has parallel stripes and lustrous colors. It comes in various, luminous shades of light or dark brown due to iron oxides. Tiger’s eye has the property of chatoyancy, meaning that when cut into a cabochon, it can shine with only a small ray of light on its surface, much like the eyes of a cat.

Also called crocidolite cat’s-eye or African cat’s-eye, the gem has a hardness of 7.0 on the Mohs Scale. Its most important deposit is in South Africa, though it is also found in western Australia, Myanmar (formerly Burma), India and California. Tiger’s eye has recently become a modern anniversary gemstone for the 9th year of marriage.

Roman soldiers wore tiger’s eye for protection in battle and the stone is said to enhance courage and bring physical strength. Tiger’s eye is also believed to offer protection during travel and dispel negative energies. The gem is said to strengthen confidence, willpower and convictions, which in turn help people to accomplish goals, increase wealth and achieve a joyful outlook. Tiger’s eye is thought to help people recognize their inner power, leading them to attain their dreams and bring passion and vitality to their lives.

Perhaps tiger eye’s greatest folklore is that it is believed to promote mental clarity and balance. The gem is said to focus the mind and teach people to see with the eye of the tiger, clearly and without illusion. It is believed that tiger eye’s soothing vibrations can generate a calming effect that diminishes unclear thinking. The stone’s subtle energies are thought to bring order, stability and discipline to life. Tiger’s eye is closely attuned to Earth energies, but its yellow highlights are linked to the sun. Because it is believed to be a bridge between Earth and sky, it is considered a tool for balance between the physical and the spiritual. As a link between Father Sky and Mother Earth, the stone’s influence is thought to be one of harmony between yin and yang.