Lesson 3: Cut Grade Categories and Taking Out the Garbage
Cut Grade Categories
Cut diamonds can be fitted into one of five categories. Not renowned for my tact, I simply call them Best, Better, Good, Junk and Garbage. Granted, retailers use more euphemistic terms. They are, nevertheless, still undefined. But, never mind what they are called. By the time we are finished, we will have dispensed entirely with all such subjective terms and we will be able to assign two precise objective numbers to any stone. These numbers will have a universal meaning. They will transcend all previous subjective designations and will be unambiguous.
But, first, consider the present situation. From the information supplied by sellers and required by truth in advertising laws, one can read between the lines of their certificates, if one knows how. Here is how, starting from the bottom up.
- If the stone is set in a mounting and sold without a certificate of any kind, you can rest assured it would grade either as Trash or Garbage.
- If it is sold with a grading report or certificate, READ IT. In its simplest form, you should still see notations relative to the stone’s weight, color, and clarity, as well as numerical values for its diameter, as well as total height or depth. These will be considered in a moment.
- If offered by a top class jeweler, it will probably be sold unmounted and accompanied by a fancier certificate listing all sorts of measurements, e.g., diameter, table size, crown height, crown angle, girdle size, pavilion angle, culet size, polish, finish, and other comments. Don’t be confused by this plethora of data. You don’t need all this to grade a stone. Junk is junk and it is obvious if you know what to look for.
Taking out the Trash and Garbage
Well cut diamonds have certain characteristics. So do Junk and Garbage. For those who can, I would suggest visiting your local shopping mall. There you’ll find a Diamondologist or Gemologist who will be happy to educate you. They have numerous stones to illustrate the different features. Look at their stones. Ask questions.
If the girdle obviously appears too thick or too thin, the table appears too large or too small, or the culet is noticeable, you are at best dealing with Junk. If you wish to confirm this, measure them or look at the numbers on the certificate for total height and diameter. The Total Height of the stone is the important number. If the height value is not between the values of 58% and 64% of the diameter, you know you are dealing with Junk or Garbage.
Diamonds are sold by nominal weight. A three quarter carat (0.75 ct) diamond must weigh at least 0.70 ct to qualify. Also, diamond cutters are not fools. They know if they leave a little extra weight on what should produce a nice 0.69 ct stone in order to produce a 0.70 ct stone, their profit will be greater. Consequently, one finds an inordinate quantity of 0.70 and 0.71 ct stones for sale. Most of these stones have been cut for weight rather than beauty, and they deserve to be called Junk.
If your stone passes the previous tests, and the Junk and Garbage have been eliminated from further consideration, it is then necessary to determine only two additional properties; crown angle and pavilion angle. If not, don’t bother. You will be wasting your time. Cut grades are based on the worst properties, and you have already found them.