Some people purchase loose stones for jewelry making, while others do so for investment purposes. Still others are looking for the perfect stone to have made into a piece of jewelry by a custom jeweler. Most gemstones are minerals, but some rocks such as lapis lazuli and organic materials like pearls or amber considered as such. Today, four stones are precious stones: diamond, emerald, ruby, and sapphire. Everything else falls under the category of semi-precious stones. When purchase loose stones, obviously should only deal with a reputable jeweler that trust, online or in person. Always get a certificate from the seller and be sure exactly what are purchasing. Diamonds are the only gemstones that have a universally accepted grading system based on the concept of the four C’s: color, cut, carat, and clarity. Clarity is determined by placing the diamond under 10X magnification. However, cut is most important for the value of a clear diamond, because without the proper cut, the diamond will not sparkle, as it should. Clarity and color are next in importance. All other gemstones grade with the naked eye. The quality of all colored stones based on the clarity and brilliance of the stone’s color, which divided into three parts: hue, saturation, and tone. Hue refers to the stone’s color, which produced in the following spectral hues: red, orange, yellow, green, blue, violet, purple and pink. Purple and pink are spectral hues, as purple lies halfway between red and blue, and pink is really a lighter shade of red. Natural stones seldom have pure hues, so these are into primary, secondary, and sometimes tertiary hues. Saturation refers to the clarity of color, or the stone’s freedom from brown or grey hues.

Emeralds

Emeralds, like all colored gemstones, are graded using four basic parameters – the four Cs of Gemstones: Color, Cut, Clarity and Crystal. The last C, crystal is a synonym that begins with C for transparency or what gemologists call diaphaneity. Before the 20th century, jewelers used the term water as in a gem of the finest water to express the combination of two qualities, color and crystal. Normally, in the grading of colored gemstones, color is by far the most important criterion. However, in the grading of emerald, crystal considered a close second. Both are necessary conditions. A fine emerald must possess not only a pure verdant green hue as described below, but also a high degree of transparency considered a top gem. In the 1960s, the American jewelry industry changed the definition of emerald to include the green vanadium-bearing beryl as emerald. As a result, vanadium emeralds purchased as emeralds in the United States recognized as such in the UK and Europe. In America, the distinction between traditional emeralds and the new vanadium kind reflected in the use of terms such as Colombian Emerald. Scientifically speaking, color divided into three components: hue, saturation and tone. Yellow and blue, the hues found adjacent to green on the spectral color wheel, are the normal secondary hues found in emerald. Emeralds occur in hues ranging from yellow-green to blue-green. The primary hue must be green. Only gems that are medium to dark in tone considered emerald. Light-toned gems 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. Emerald tends to have numerous inclusions and surface breaking fissures. Emerald graded by eye. Thus, if an emerald has no visible inclusions to the eye it considered flawless. Stones that lack surface breaking fissures are extremely rare and therefore almost all emeralds are treated, oiled, to enhance the apparent clarity. Eye-clean stones of a vivid primary green hue with no more than 15% of any secondary hue or combination of a medium-dark tone command the highest prices.6 This relative crystal non-uniformity makes emeralds more likely than other gemstones to be cut into cabochons, rather than faceted shapes.