 
The birthstone for April is the diamond.Diamond is the best known gemstone, famous for its remarkable brilliance. Ancient civilizations were fascinated by the exceptional hardness of diamond, although colored gems were regarded as more aesthetically pleasing. The Greek philosopher, Plato, called diamond the "noblest" of all gems. Diamond was extremely rare up to the eighteenth century and was only fully appreciated after the modern type of brilliant cut, which shows it in all of its glory, was developed at the beginning of the twentieth century. In most cases, diamond is almost colorless, but can also appear as yellow, brown, yellow-brown. Very rarely, diamonds may also be pink to reddish, blue, blue-gray, pale green, or violet. Throughout history, diamonds were consistently linked with mystical powers, courage, and virtue.Mohs hardness: 10 Refractive Index: 2.41 Specific Gravity: 3.52 The toughness of diamonds is good. Diamond may be cleaned by any of these methods: steaming, ultrasonic, boiling, jewelry cleaner, soap, or an untreated cloth. When buying a diamond, consider the following 4-C's: Cut The cut of a diamond has the greatest influence on the diamond's fire and brilliance. A round, brilliant cut diamond has fifty-eight (58) facets. When well proportioned, this shape best shows the brilliance of the stone because it allows the most light to be reflected back to the eye of the observer. Stones that appear lifeless or seem dark in the center are probably poorly cut. Carat The term carat comes from the ancient practice of weighing diamonds against the seeds of the carob tree. The system was eventually standardized, and one carat was fixed at 0.2 grams. One carat is divided into 100 points, so a quarter carat diamond is 25 points, or 0.25 carats. Although carat is a unit of weight, not size, the carat weight of a diamond has come to refer to particular sizes. If properly cut, diamonds of the same weight should be about the same size. These sizes don't apply to other gems, however, because they have different specific gravities than diamonds. Color Diamonds can cover the entire spectrum of colors. The majority, however, range from those with a barely perceptible yellow or brownish tint, up to those that are very rare and described as colorless. Colorless diamonds are the most desirable since they allow the most reflection of light. Off white diamonds absorb light, inhibiting brilliance. You can best observe diamond color by placing the stone table side down on a flat, white surface or grading trough, and examining it from different angles. Next, place it pavilion side down with the culet facing you, and examine it through the pavilion facets. Clarity Most diamonds contain minute traces of non-crystallized carbon and internal stress fractures. Called inclusions, most of these are not apparent to the naked eye, but can be seen in loose stones under magnification. Perfect clarity means that no inclusions are discernible when the diamond is examined under a 10X lens. Inclusions greatly affect the beauty and value of a diamond because they absorb the light rather than allowing it to be reflected back through the front of the stone. How much they reduce the value of a diamond depends on their size and number, and their position within the stone. An inclusion in the center of a diamond beneath the table is more visible than one near the edge. It also may be mirrored many times by adjoining facets. The GIA clarity grading scale gives a description of each grade.
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