A gemstone or gem (also called a precious or semi-precious stone, or jewel) is a piece of mineral, which is used to make jewelry or other ornaments. However certain rocks, (such as Lapis lazuli) and organic materials (such as amber or jet) are not minerals, but are still used for jewelry, and are therefore often considered being gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their physical properties that have aesthetic value.
Characteristics and Classification
In modern usage the precious stones are diamond, ruby, sapphire and emerald, with all other gemstones being semi-precious. This distinction is unscientific and reflects their quality; all the gemstones are translucent with fine color in their purest forms, except for the colorless diamond. Other stones are classified by their color, translucency and hardness. The traditional distinction does not necessarily reflect modern values, for example, while garnets are relatively inexpensive, a green garnet can be far more valuable than a mid-quality emerald.
Stones which are opaque such as Opal, Turquoise, Variscite, etc. are commonly cut as cabochons. These gems are designed to show the stone's color or surface properties as in opal and star sapphires. Gems which are transparent are normally faceted, a method which shows the optical properties of the stone's interior to its best advantage by maximizing reflected light which is perceived by the viewer as sparkle.
Color is the most obvious and attractive feature of gemstones. The color of any material is due to the nature of light itself. Daylight, often called white light, is actually a mixture of different colors of light. When light passes through a material, some of the light may be absorbed, while the rest passes through. The part that is not absorbed reaches the eye as white light minus the absorbed colors. A ruby appears red because it absorbs all the other colors of white light (blue, yellow, green, etc.) except red.
Alexandrite and other varieties of chrysoberyl
Jade - jadeite and nephrite
Tanzanite and other varieties of zoisite
Most Expensive Gemstones:
The most expensive gems are known as the "Big Four". They are known as Diamond, Ruby, Sapphire and Emerald.
The diamond is the hardest and one of the most valued gemstone. Diamonds are the symbol of innocence and constancy. Diamonds have been prized as Crown jewels; they are used today as an engagement ring. It is said diamonds are good for coughs and mucus problems. The finest quality as per color grading is totally colorless; it is absolutely free from any color. The next grade has a very slight trace of color, which can be observed by any expert diamond values/grading laboratory.
Some of the precious diamonds are priced at per-carat basis and are “The Graff Pink Diamond” Laurence Graff bought it in an auction for $45.6 million; the highest amount is ever paid at an auction for a gem. . It has a weight of 24.78-carats and is emerald-cut. “The Allnatt Diamond” Its owner Major Alfred Ernest Allnatt set and sold it in 1996 for over 3 million dollars and has weight of 101.29 carats. “The Heart of Eternity” the Splendor of Diamonds exhibition describes the Heart of Eternity as Fancy Intense Blue but Gemological Institute of America graded it “Fancy Vivid Blue”. This diamond is 27.64 carats and its color is considered to be extremely rare. It will cost around $16 million.
Diamond does come in yellowish colors, green and blue, but the clear or white is the most used in jewelry. Most diamonds come from South Africa.
Ruby has been the world's most valued gemstone for thousands of years. Ruby was said to be the most precious of the twelve stones God created when he created all things and this "lord of gems" was placed on Aaron's neck by God's command. Ruby is "king and leader of precious stones”. Prices of rubies are primarily determined by color. The brightest and most valuable "red" called pigeon blood-red, commands a huge premium over other rubies of similar quality.
The Heart of the Kingdom Ruby is 40.63 carats and heart-shaped, this piece is worth about $15 million dollars and is an expensive one.
Colors of Ruby are Red, may be brownish, purplish or pinkish.
Emeralds are fascinating gemstones. They have the most beautiful, most intense and most radiant green that can possibly be imagined: emerald green. In top quality, fine emeralds are even more valuable than diamonds. The rich green color of emerald is the color of spring; the ancients prized it as the gemstone symbolizing love and rebirth. Emerald is said to quicken the intelligence as well as the heart.
A solitaire emerald gemstone that is 33.02 carats, also surrounded by half-moon diamonds on each side is more or less $2.14 to $2.15 million dollars.
The most beautiful color of Emerald is green and others are yellow, purple, red, white, cyan and orange. Emeralds occur in hues ranging from yellow-green to blue-green. The primary hue must, of course, be green. Only gems that are medium to dark in tone are considered emerald. Light-toned gems are known by the species name, green beryl. In addition, the hue must be bright (vivid). Gray is the normal saturation modifier or mask found in emerald. A grayish green hue is a dull green.
Sapphire is the most precious, strongest, fastest acting and valuable blue gemstone. It is a very desirable gemstone due to its excellent color, hardness, durability, and luster. Sapphire without any color prefix refers to the blue variety of the mineral Corundum. However, the term Sapphire encompasses all other gem varieties and colors of Corundum as well, excluding Ruby, the red variety of Corundum, which has its own name since antiquity.
The cost of natural sapphires varies depending on their color, clarity, size, cut, and overall quality, as well as their geographic origin. Pinkish orange is the rarest color for sapphire, which also makes it the most valuable. Its color has been described as a pinkish orange and it usually sells for about $5,000 a carat.
Sapphire is available in different colors like blue, white, yellow, orange, green, purple, pink.