Diamonds, like all gems, are evaluated for worth and classification in carat weight , which literally translates to 200 milligrams or one-fifth of a gram per metric carat. Anything less than one whole carat is measured in points , as there are one hundred points to a whole carat. Thus a 50 point carat diamond is actually a ½ carat diamond, a 75 point diamond is really a ¾ carat diamond, and so forth. Carat refers to the weight of the stone- not its size- so do not be surprised to see two differently sized stones of different kind in the same size. Diamonds do not weigh the same per carat weight as emeralds or rubies or any other kind of stone, as weight is a question of density and mineral composition- not mass. The purchaser of the diamond pays per carat weight of the particular stone as it was weighed before being set or mounted and respective of its four classification grades.

Most fine diamonds weighing one carat or more are evaluated by a respected laboratory and are set a diamond grading report that both certifies the diamond as authentic and describes it. This description will include all the pertinent information you will need to have to know that not only in the document legal, it also pertains to the specific stone you are buying. “Switching” stones with one set of documents to another is a common event, especially since most people aren't familiar with the potential problems involved. The reports description of the stone will include the minute details of type and placement of every blemish or inclusion for this reason. The report should have a certificate number and date of issue, and in the future this will enable you to verify the information about your diamond. There are no approximate carat or point weights in this evaluation - even with stones only slightly different in weight. Every point counts in value and cost.

Carat weight is usually a good method of evaluating a diamonds market worth, as this is the most easily discernable aspect of any stone and it is homogonous everywhere. Knowing first the diamonds carat, then its color grading and clarity grading, can give you a reasonably accurate estimation of what the diamond should sell for. Any diamond highly color-graded and clarity-graded will cost far more per carat weight because it is rare. However, this system is not entirely simple, as smaller diamonds are available in multitudes and larger stones are hardly ever found. Thus you may have a 1 carat diamond that costs 2000$ and a same-grade stone of 3 carats that costs far more than 6000$, because a 3 carat diamond of this grade is uncommon. There are uneven leaps of value respective of the diamonds weight and availability. Therefore the 3 carat stone does not weigh exactly three times the 1 carat, despite the fact that they share the same classification category, but actually costs five or six times as much, because of its rarity. A point diamond, even if it's a 98 or 99 point diamond will cost far less than a full one-carat diamond, even if such a distinction may seem subtle to the point of invisibility.

Another anomaly in this kind of classification is the diamonds real size , as opposed to the diamonds apparent size . As you will see in the following text on cutting techniques, a stone maybe made to appear larger or smaller than it really is. The various angles and general composition of the stone may therefore be slightly confusing. A diamond's “ spread ”-a term widely used in this field- is not the diamonds carat weight , but the diamonds diameter. This is what makes the stone appear either larger or smaller, and this is also a good opportunity for those people who would like a full carat stone, but can't afford it. A one-carat spread diamond may look like a full carat diamond, but in actuality weigh several points less than a full carat and be far less expensive. Trusting your eyes for this evaluation is foolhardy if you are not a professional. The apparent size of any stone depends on so many parameters that it is hardly to be factored into cost. Apparent size is influenced by cut, diameter width, girdle width and even color, so in this regard be sure you are paying per carat weight only.

There are many ways in which an unsuspecting purchaser may be tricked into buying a stone that weighs less than advertised. Also, many stones are already mounted at the time of the purchase; often there are several stones in the same piece. You should remember that each stone has been weighed individually and respective of their various grades- before mounting. Never buy a ring that has several stones in it with information only about its total weight. Total weight refers to the sum weight of all the stones that are in the piece, and this is no indicator of cost. It is also a violation of the Federal Trade Commission's ruling and therefore immediately suspect. The separate carat or point weights of each stone in the piece should be indicated and documented by their grades, so that so may know exactly what you are buying. Such a description will detail the center stone's weight, each of the side stone's weight and a sum total of the piece's weight. This is hugely influential to cost, so alertness to this fact is crucial.